diff --git a/apps/dav/appinfo/v1/publicwebdav.php b/apps/dav/appinfo/v1/publicwebdav.php
index 2eaf05ca2d9b6..0d57b978dc70f 100644
--- a/apps/dav/appinfo/v1/publicwebdav.php
+++ b/apps/dav/appinfo/v1/publicwebdav.php
@@ -47,7 +47,8 @@
 	Server::get(IRequest::class),
 	Server::get(\OCP\Share\IManager::class),
 	Server::get(ISession::class),
-	Server::get(IThrottler::class)
+	Server::get(IThrottler::class),
+	Server::get(IUserSession::class),
 );
 $authPlugin = new \Sabre\DAV\Auth\Plugin($authBackend);
 
diff --git a/apps/dav/appinfo/v2/publicremote.php b/apps/dav/appinfo/v2/publicremote.php
index facc4041bccde..7d43fef21b1f1 100644
--- a/apps/dav/appinfo/v2/publicremote.php
+++ b/apps/dav/appinfo/v2/publicremote.php
@@ -64,6 +64,7 @@
 	Server::get(IThrottler::class),
 	Server::get(LoggerInterface::class),
 	Server::get(IURLGenerator::class),
+	Server::get(IUserSession::class),
 );
 $authPlugin = new \Sabre\DAV\Auth\Plugin($authBackend);
 
diff --git a/apps/dav/lib/Connector/LegacyPublicAuth.php b/apps/dav/lib/Connector/LegacyPublicAuth.php
index 03d18853de0c6..378bff6f17f7d 100644
--- a/apps/dav/lib/Connector/LegacyPublicAuth.php
+++ b/apps/dav/lib/Connector/LegacyPublicAuth.php
@@ -11,6 +11,7 @@
 use OCP\Defaults;
 use OCP\IRequest;
 use OCP\ISession;
+use OCP\IUserSession;
 use OCP\Security\Bruteforce\IThrottler;
 use OCP\Share\Exceptions\ShareNotFound;
 use OCP\Share\IManager;
@@ -28,10 +29,11 @@ class LegacyPublicAuth extends AbstractBasic {
 	private ?IShare $share = null;
 
 	public function __construct(
-		private IRequest $request,
-		private IManager $shareManager,
-		private ISession $session,
-		private IThrottler $throttler,
+		private readonly IRequest $request,
+		private readonly IManager $shareManager,
+		private readonly ISession $session,
+		private readonly IThrottler $throttler,
+		private readonly IUserSession $userSession,
 	) {
 		// setup realm
 		$defaults = new Defaults();
@@ -62,7 +64,7 @@ protected function validateUserPass($username, $password) {
 
 		$this->share = $share;
 
-		\OC_User::setIncognitoMode(true);
+		$this->userSession->setIncognitoMode(true);
 
 		// check if the share is password protected
 		if ($share->getPassword() !== null) {
diff --git a/apps/dav/lib/Connector/Sabre/PublicAuth.php b/apps/dav/lib/Connector/Sabre/PublicAuth.php
index f8b19b36d6f63..ae6dd66e4d849 100644
--- a/apps/dav/lib/Connector/Sabre/PublicAuth.php
+++ b/apps/dav/lib/Connector/Sabre/PublicAuth.php
@@ -15,6 +15,7 @@
 use OCP\IRequest;
 use OCP\ISession;
 use OCP\IURLGenerator;
+use OCP\IUserSession;
 use OCP\Security\Bruteforce\IThrottler;
 use OCP\Security\Bruteforce\MaxDelayReached;
 use OCP\Share\Exceptions\ShareNotFound;
@@ -42,12 +43,13 @@ class PublicAuth extends AbstractBasic {
 	private ?IShare $share = null;
 
 	public function __construct(
-		private IRequest $request,
-		private IManager $shareManager,
-		private ISession $session,
-		private IThrottler $throttler,
-		private LoggerInterface $logger,
-		private IURLGenerator $urlGenerator,
+		private readonly IRequest $request,
+		private readonly IManager $shareManager,
+		private readonly ISession $session,
+		private readonly IThrottler $throttler,
+		private readonly LoggerInterface $logger,
+		private readonly IURLGenerator $urlGenerator,
+		private readonly IUserSession $userSession,
 	) {
 		// setup realm
 		$defaults = new Defaults();
@@ -134,7 +136,7 @@ private function checkToken(): array {
 		}
 
 		$this->share = $share;
-		\OC_User::setIncognitoMode(true);
+		$this->userSession->setIncognitoMode(true);
 
 		// If already authenticated
 		if ($this->isShareInSession($share)) {
@@ -172,7 +174,7 @@ protected function validateUserPass($username, $password) {
 			return false;
 		}
 
-		\OC_User::setIncognitoMode(true);
+		$this->userSession->setIncognitoMode(true);
 
 		// check if the share is password protected
 		if ($share->getPassword() !== null) {
diff --git a/apps/dav/tests/unit/Connector/LegacyPublicAuthTest.php b/apps/dav/tests/unit/Connector/LegacyPublicAuthTest.php
index 8fc54de645a2e..3f9d7dac831ec 100644
--- a/apps/dav/tests/unit/Connector/LegacyPublicAuthTest.php
+++ b/apps/dav/tests/unit/Connector/LegacyPublicAuthTest.php
@@ -9,9 +9,13 @@
 namespace OCA\DAV\Tests\unit\Connector;
 
 use OCA\DAV\Connector\LegacyPublicAuth;
+use OCP\Files\ISetupManager;
 use OCP\IRequest;
 use OCP\ISession;
+use OCP\IUser;
+use OCP\IUserSession;
 use OCP\Security\Bruteforce\IThrottler;
+use OCP\Server;
 use OCP\Share\Exceptions\ShareNotFound;
 use OCP\Share\IManager;
 use OCP\Share\IShare;
@@ -26,7 +30,7 @@ class LegacyPublicAuthTest extends TestCase {
 	private IManager&MockObject $shareManager;
 	private IThrottler&MockObject $throttler;
 	private LegacyPublicAuth $auth;
-	private string|false $oldUser;
+	private ?IUser $oldUser;
 
 	protected function setUp(): void {
 		parent::setUp();
@@ -40,20 +44,21 @@ protected function setUp(): void {
 			$this->request,
 			$this->shareManager,
 			$this->session,
-			$this->throttler
+			$this->throttler,
+			$this->createMock(IUserSession::class),
 		);
 
 		// Store current user
-		$this->oldUser = \OC_User::getUser();
+		$this->oldUser = Server::get(IUserSession::class)->getUser() ?? null;
 	}
 
 	protected function tearDown(): void {
-		\OC_User::setIncognitoMode(false);
+		Server::get(IUserSession::class)->setIncognitoMode(false);
 
 		// Set old user
-		\OC_User::setUserId($this->oldUser ?: null);
-		if ($this->oldUser !== false) {
-			\OC_Util::setupFS($this->oldUser);
+		self::setUserId($this->oldUser?->getUID());
+		if ($this->oldUser !== null) {
+			Server::get(ISetupManager::class)->setupForUser($this->oldUser);
 		}
 
 		parent::tearDown();
diff --git a/apps/dav/tests/unit/Connector/Sabre/PublicAuthTest.php b/apps/dav/tests/unit/Connector/Sabre/PublicAuthTest.php
index 2f18b4305087e..136a6fb584aa0 100644
--- a/apps/dav/tests/unit/Connector/Sabre/PublicAuthTest.php
+++ b/apps/dav/tests/unit/Connector/Sabre/PublicAuthTest.php
@@ -9,10 +9,14 @@
 namespace OCA\DAV\Tests\unit\Connector;
 
 use OCA\DAV\Connector\Sabre\PublicAuth;
+use OCP\Files\ISetupManager;
 use OCP\IRequest;
 use OCP\ISession;
 use OCP\IURLGenerator;
+use OCP\IUser;
+use OCP\IUserSession;
 use OCP\Security\Bruteforce\IThrottler;
+use OCP\Server;
 use OCP\Share\Exceptions\ShareNotFound;
 use OCP\Share\IManager;
 use OCP\Share\IShare;
@@ -35,8 +39,7 @@ class PublicAuthTest extends \Test\TestCase {
 	private LoggerInterface&MockObject $logger;
 	private IURLGenerator&MockObject $urlGenerator;
 	private PublicAuth $auth;
-
-	private bool|string $oldUser;
+	private ?IUser $oldUser;
 
 	protected function setUp(): void {
 		parent::setUp();
@@ -55,19 +58,20 @@ protected function setUp(): void {
 			$this->throttler,
 			$this->logger,
 			$this->urlGenerator,
+			$this->createMock(IUserSession::class),
 		);
 
 		// Store current user
-		$this->oldUser = \OC_User::getUser();
+		$this->oldUser = Server::get(IUserSession::class)->getUser() ?? null;
 	}
 
 	protected function tearDown(): void {
-		\OC_User::setIncognitoMode(false);
+		Server::get(IUserSession::class)->setIncognitoMode(false);
 
 		// Set old user
-		\OC_User::setUserId($this->oldUser);
-		if ($this->oldUser !== false) {
-			\OC_Util::setupFS($this->oldUser);
+		self::setUserId($this->oldUser?->getUID());
+		if ($this->oldUser !== null) {
+			Server::get(ISetupManager::class)->setupForUser($this->oldUser);
 		}
 
 		parent::tearDown();
diff --git a/apps/federatedfilesharing/tests/TestCase.php b/apps/federatedfilesharing/tests/TestCase.php
index 5132a2c8fd0d6..5c0718e640687 100644
--- a/apps/federatedfilesharing/tests/TestCase.php
+++ b/apps/federatedfilesharing/tests/TestCase.php
@@ -11,6 +11,7 @@
 use OC\Files\Filesystem;
 use OC\Group\Database;
 use OCP\Files\IRootFolder;
+use OCP\Files\ISetupManager;
 use OCP\IGroupManager;
 use OCP\IUserManager;
 use OCP\IUserSession;
@@ -56,8 +57,9 @@ public static function tearDownAfterClass(): void {
 			$user->delete();
 		}
 
-		\OC_Util::tearDownFS();
-		\OC_User::setUserId('');
+		$setupManager = Server::get(ISetupManager::class);
+		$setupManager->tearDown();
+		self::setUserId('');
 		Filesystem::tearDown();
 
 		// reset backend
@@ -69,13 +71,13 @@ public static function tearDownAfterClass(): void {
 		parent::tearDownAfterClass();
 	}
 
-	protected static function loginHelper(string $user, bool $create = false, bool $password = false) {
+	protected static function loginHelper(string $user, bool $create = false, bool $password = false): void {
 		if ($password === false) {
 			$password = $user;
 		}
 
+		$userManager = Server::get(IUserManager::class);
 		if ($create) {
-			$userManager = Server::get(IUserManager::class);
 			$groupManager = Server::get(IGroupManager::class);
 
 			$userObject = $userManager->createUser($user, $password);
@@ -84,14 +86,16 @@ protected static function loginHelper(string $user, bool $create = false, bool $
 			if ($group && $userObject) {
 				$group->addUser($userObject);
 			}
+		} else {
+			$userObject = $userManager->get($user);
 		}
 
-		\OC_Util::tearDownFS();
+		$setupManager = Server::get(ISetupManager::class);
+		$setupManager->tearDown();
 		Server::get(IUserSession::class)->setUser(null);
 		Filesystem::tearDown();
 		Server::get(IUserSession::class)->login($user, $password);
 		Server::get(IRootFolder::class)->getUserFolder($user);
-
-		\OC_Util::setupFS($user);
+		$setupManager->setupForUser($userObject);
 	}
 }
diff --git a/apps/files/tests/Service/TagServiceTest.php b/apps/files/tests/Service/TagServiceTest.php
index 1b3e0898b334a..a31c80e242a84 100644
--- a/apps/files/tests/Service/TagServiceTest.php
+++ b/apps/files/tests/Service/TagServiceTest.php
@@ -41,7 +41,7 @@ protected function setUp(): void {
 		$this->user = static::getUniqueID('user');
 		$this->activityManager = $this->createMock(IManager::class);
 		Server::get(IUserManager::class)->createUser($this->user, 'test');
-		\OC_User::setUserId($this->user);
+		self::setUserId($this->user);
 		\OC_Util::setupFS($this->user);
 		$user = $this->createMock(IUser::class);
 		$this->userSession = $this->createMock(IUserSession::class);
@@ -69,7 +69,7 @@ protected function getTagService(array $methods = []): TagService&MockObject {
 	}
 
 	protected function tearDown(): void {
-		\OC_User::setUserId('');
+		self::setUserId('');
 		$user = Server::get(IUserManager::class)->get($this->user);
 		if ($user !== null) {
 			$user->delete();
diff --git a/apps/files_external/lib/Lib/Storage/SFTP.php b/apps/files_external/lib/Lib/Storage/SFTP.php
index 6504ea610f345..059e1e5d42b30 100644
--- a/apps/files_external/lib/Lib/Storage/SFTP.php
+++ b/apps/files_external/lib/Lib/Storage/SFTP.php
@@ -17,6 +17,7 @@
 use OCP\Constants;
 use OCP\Files\FileInfo;
 use OCP\Files\IMimeTypeDetector;
+use OCP\IUserSession;
 use OCP\Server;
 use phpseclib\Net\SFTP\Stream;
 
@@ -182,13 +183,12 @@ private function absPath(string $path): string {
 
 	private function hostKeysPath(): string|false {
 		try {
-			$userId = \OC_User::getUser();
-			if ($userId === false) {
+			$user = Server::get(IUserSession::class)->getUser();
+			if ($user === null) {
 				return false;
 			}
 
-			$view = new View('/' . $userId . '/files_external');
-
+			$view = new View('/' . $user->getUID() . '/files_external');
 			return $view->getLocalFile('ssh_hostKeys');
 		} catch (\Exception $e) {
 		}
diff --git a/apps/files_external/lib/Migration/DummyUserSession.php b/apps/files_external/lib/Migration/DummyUserSession.php
index 1ebf0e1ec4f85..bd69a98ea5937 100644
--- a/apps/files_external/lib/Migration/DummyUserSession.php
+++ b/apps/files_external/lib/Migration/DummyUserSession.php
@@ -9,6 +9,7 @@
 
 use OCP\IUser;
 use OCP\IUserSession;
+use Override;
 
 class DummyUserSession implements IUserSession {
 
@@ -54,4 +55,13 @@ public function getImpersonatingUserID() : ?string {
 	public function setImpersonatingUserID(bool $useCurrentUser = true): void {
 		//no OP
 	}
+
+	#[Override]
+	public function setIncognitoMode(bool $incognitoMode): void {
+	}
+
+	#[Override]
+	public function isIncognitoMode(): bool {
+		return false;
+	}
 }
diff --git a/apps/files_sharing/lib/Controller/ShareController.php b/apps/files_sharing/lib/Controller/ShareController.php
index 0e0e98ef2d5ab..12681f16020b6 100644
--- a/apps/files_sharing/lib/Controller/ShareController.php
+++ b/apps/files_sharing/lib/Controller/ShareController.php
@@ -40,6 +40,7 @@
 use OCP\ISession;
 use OCP\IURLGenerator;
 use OCP\IUserManager;
+use OCP\IUserSession;
 use OCP\Security\Events\GenerateSecurePasswordEvent;
 use OCP\Security\ISecureRandom;
 use OCP\Security\PasswordContext;
@@ -78,6 +79,7 @@ public function __construct(
 		protected ISecureRandom $secureRandom,
 		protected Defaults $defaults,
 		private IPublicShareTemplateFactory $publicShareTemplateFactory,
+		private IUserSession $userSession,
 	) {
 		parent::__construct($appName, $request, $session, $urlGenerator);
 	}
@@ -299,7 +301,7 @@ private function validateShare(IShare $share) {
 	#[PublicPage]
 	#[NoCSRFRequired]
 	public function showShare($path = ''): TemplateResponse {
-		\OC_User::setIncognitoMode(true);
+		$this->userSession->setIncognitoMode(true);
 
 		// Check whether share exists
 		try {
@@ -353,7 +355,7 @@ public function showShare($path = ''): TemplateResponse {
 	#[NoCSRFRequired]
 	#[NoSameSiteCookieRequired]
 	public function downloadShare(string $token, ?string $files = null, string $path = ''): NotFoundResponse|RedirectResponse|DataResponse {
-		\OC_User::setIncognitoMode(true);
+		$this->userSession->setIncognitoMode(true);
 
 		$share = $this->shareManager->getShareByToken($token);
 
diff --git a/apps/files_sharing/lib/Updater.php b/apps/files_sharing/lib/Updater.php
index 019542fa6bf9a..3d17d1ab61f87 100644
--- a/apps/files_sharing/lib/Updater.php
+++ b/apps/files_sharing/lib/Updater.php
@@ -14,8 +14,10 @@
 use OCP\Files\Folder;
 use OCP\Files\Mount\IMountManager;
 use OCP\Files\NotFoundException;
+use OCP\IUserSession;
 use OCP\Server;
 use OCP\Share\IShare;
+use RuntimeException;
 
 class Updater {
 
@@ -139,14 +141,18 @@ private static function moveShareInOrOutOfShare($path): void {
 	 * @param string $newPath new path relative to data/user/files
 	 */
 	private static function renameChildren($oldPath, $newPath) {
-		$absNewPath = Filesystem::normalizePath('/' . \OC_User::getUser() . '/files/' . $newPath);
-		$absOldPath = Filesystem::normalizePath('/' . \OC_User::getUser() . '/files/' . $oldPath);
+		$user = Server::get(IUserSession::class)->getUser();
+		if ($user === null) {
+			throw new RuntimeException('Unable to find current user');
+		}
+		$absNewPath = Filesystem::normalizePath('/' . $user->getUID() . '/files/' . $newPath);
+		$absOldPath = Filesystem::normalizePath('/' . $user->getUID() . '/files/' . $oldPath);
 
 		$mountManager = Filesystem::getMountManager();
-		$mountedShares = $mountManager->findIn('/' . \OC_User::getUser() . '/files/' . $oldPath);
+		$mountedShares = $mountManager->findIn('/' . $user->getUID() . '/files/' . $oldPath);
 		foreach ($mountedShares as $mount) {
 			/** @var MountPoint $mount */
-			if ($mount->getStorage()->instanceOfStorage(ISharedStorage::class)) {
+			if ($mount->getStorage()->instanceOfStorage(\OCP\Files\Storage\ISharedStorage::class)) {
 				$mountPoint = $mount->getMountPoint();
 				$target = str_replace($absOldPath, $absNewPath, $mountPoint);
 				$mount->moveMount($target);
diff --git a/apps/files_sharing/tests/Controller/ShareControllerTest.php b/apps/files_sharing/tests/Controller/ShareControllerTest.php
index 4e724a45a90f3..53d554f6e5598 100644
--- a/apps/files_sharing/tests/Controller/ShareControllerTest.php
+++ b/apps/files_sharing/tests/Controller/ShareControllerTest.php
@@ -42,6 +42,7 @@
 use OCP\IURLGenerator;
 use OCP\IUser;
 use OCP\IUserManager;
+use OCP\IUserSession;
 use OCP\Security\ISecureRandom;
 use OCP\Server;
 use OCP\Share\Exceptions\ShareNotFound;
@@ -64,6 +65,7 @@ class ShareControllerTest extends \Test\TestCase {
 	private IL10N&MockObject $l10n;
 	private IConfig&MockObject $config;
 	private ISession&MockObject $session;
+	private IUserSession&MockObject $userSession;
 	private Defaults&MockObject $defaults;
 	private IAppConfig&MockObject $appConfig;
 	private Manager&MockObject $shareManager;
@@ -85,6 +87,7 @@ protected function setUp(): void {
 		$this->shareManager = $this->createMock(Manager::class);
 		$this->urlGenerator = $this->createMock(IURLGenerator::class);
 		$this->session = $this->createMock(ISession::class);
+		$this->userSession = $this->createMock(IUserSession::class);
 		$this->previewManager = $this->createMock(IPreview::class);
 		$this->config = $this->createMock(IConfig::class);
 		$this->appConfig = $this->createMock(IAppConfig::class);
@@ -141,6 +144,7 @@ protected function setUp(): void {
 			$this->secureRandom,
 			$this->defaults,
 			$this->publicShareTemplateFactory,
+			$this->userSession,
 		);
 
 
@@ -157,7 +161,7 @@ protected function setUp(): void {
 
 	protected function tearDown(): void {
 		\OC_Util::tearDownFS();
-		\OC_User::setUserId('');
+		self::setUserId('');
 		Filesystem::tearDown();
 		$user = Server::get(IUserManager::class)->get($this->user);
 		if ($user !== null) {
@@ -168,7 +172,7 @@ protected function tearDown(): void {
 		Server::get(ISession::class)->set('public_link_authenticated', '');
 
 		// Set old user
-		\OC_User::setUserId($this->oldUser);
+		self::setUserId($this->oldUser);
 		\OC_Util::setupFS($this->oldUser);
 		parent::tearDown();
 	}
diff --git a/apps/files_sharing/tests/TestCase.php b/apps/files_sharing/tests/TestCase.php
index 6b72ecb259cab..d6d1d7a890780 100644
--- a/apps/files_sharing/tests/TestCase.php
+++ b/apps/files_sharing/tests/TestCase.php
@@ -18,6 +18,7 @@
 use OCA\Files_Sharing\MountProvider;
 use OCP\Files\Config\IMountProviderCollection;
 use OCP\Files\IRootFolder;
+use OCP\Files\ISetupManager;
 use OCP\IDBConnection;
 use OCP\IGroupManager;
 use OCP\IUserManager;
@@ -153,8 +154,8 @@ public static function tearDownAfterClass(): void {
 			$group->delete();
 		}
 
-		\OC_Util::tearDownFS();
-		\OC_User::setUserId('');
+		Server::get(ISetupManager::class)->tearDown();
+		self::setUserId('');
 		Filesystem::tearDown();
 
 		// reset backend
diff --git a/apps/files_trashbin/lib/Trashbin.php b/apps/files_trashbin/lib/Trashbin.php
index d578e14238672..46830ce7328ac 100644
--- a/apps/files_trashbin/lib/Trashbin.php
+++ b/apps/files_trashbin/lib/Trashbin.php
@@ -15,7 +15,6 @@
 use OC\Files\Node\NonExistingFolder;
 use OC\Files\View;
 use OC\User\NoUserException;
-use OC_User;
 use OCA\FederatedFileSharing\FederatedShareProvider;
 use OCA\Files_Trashbin\Command\Expire;
 use OCA\Files_Trashbin\Events\BeforeNodeRestoredEvent;
@@ -47,6 +46,7 @@
 use OCP\IURLGenerator;
 use OCP\IUser;
 use OCP\IUserManager;
+use OCP\IUserSession;
 use OCP\Lock\ILockingProvider;
 use OCP\Lock\LockedException;
 use OCP\Server;
@@ -78,24 +78,27 @@ public static function ensureFileScannedHook(Node $node): void {
 	 * owners files folder
 	 *
 	 * @param string $filename
-	 * @return array
+	 * @return array{?string, ?string}
 	 * @throws NoUserException
 	 */
-	public static function getUidAndFilename($filename) {
+	public static function getUidAndFilename(string $filename): array {
 		$uid = Filesystem::getOwner($filename);
 		$userManager = Server::get(IUserManager::class);
-		// if the user with the UID doesn't exists, e.g. because the UID points
+		// if the user with the UID doesn't exist, e.g. because the UID points
 		// to a remote user with a federated cloud ID we use the current logged-in
 		// user. We need a valid local user to move the file to the right trash bin
+		$user = Server::get(IUserSession::class)->getUser();
 		if (!$userManager->userExists($uid)) {
-			$uid = OC_User::getUser();
-		}
-		if (!$uid) {
-			// no owner, usually because of share link from ext storage
-			return [null, null];
+			if ($user === null) {
+				// no owner, usually because of share link from ext storage
+				return [null, null];
+			}
+			$uid = $user->getUID();
 		}
+		$sessionUid = $user?->getUID();
+
 		Filesystem::initMountPoints($uid);
-		if ($uid !== OC_User::getUser()) {
+		if ($uid !== $sessionUid) {
 			$info = Filesystem::getFileInfo($filename);
 			$ownerView = new View('/' . $uid . '/files');
 			try {
@@ -396,20 +399,20 @@ private static function getConfiguredTrashbinSize(string $user): int|float {
 	 */
 	private static function retainVersions($filename, $owner, $ownerPath, $timestamp) {
 		if (Server::get(IAppManager::class)->isEnabledForUser('files_versions') && !empty($ownerPath)) {
-			$user = OC_User::getUser();
+			$user = Server::get(IUserSession::class)->getUser();
 			$rootView = new View('/');
 
 			if ($rootView->is_dir($owner . '/files_versions/' . $ownerPath)) {
-				if ($owner !== $user) {
+				if ($owner !== $user->getUID()) {
 					self::copy_recursive($owner . '/files_versions/' . $ownerPath, $owner . '/files_trashbin/versions/' . static::getTrashFilename(basename($ownerPath), $timestamp), $rootView);
 				}
-				self::move($rootView, $owner . '/files_versions/' . $ownerPath, $user . '/files_trashbin/versions/' . static::getTrashFilename($filename, $timestamp));
+				self::move($rootView, $owner . '/files_versions/' . $ownerPath, $user->getUID() . '/files_trashbin/versions/' . static::getTrashFilename($filename, $timestamp));
 			} elseif ($versions = Storage::getVersions($owner, $ownerPath)) {
 				foreach ($versions as $v) {
-					if ($owner !== $user) {
+					if ($owner !== $user->getUID()) {
 						self::copy($rootView, $owner . '/files_versions' . $v['path'] . '.v' . $v['version'], $owner . '/files_trashbin/versions/' . static::getTrashFilename($v['name'] . '.v' . $v['version'], $timestamp));
 					}
-					self::move($rootView, $owner . '/files_versions' . $v['path'] . '.v' . $v['version'], $user . '/files_trashbin/versions/' . static::getTrashFilename($filename . '.v' . $v['version'], $timestamp));
+					self::move($rootView, $owner . '/files_versions' . $v['path'] . '.v' . $v['version'], $user->getUID() . '/files_trashbin/versions/' . static::getTrashFilename($filename . '.v' . $v['version'], $timestamp));
 				}
 			}
 		}
@@ -470,17 +473,17 @@ private static function copy(View $view, $source, $target) {
 	 * @return bool true on success, false otherwise
 	 */
 	public static function restore($file, $filename, $timestamp) {
-		$user = OC_User::getUser();
-		if (!$user) {
+		$user = Server::get(IUserSession::class)->getUser();
+		if ($user === null) {
 			throw new \Exception('Tried to restore a file while not logged in');
 		}
-		$view = new View('/' . $user);
+		$view = new View('/' . $user->getUID());
 
 		$location = '';
 		if ($timestamp) {
-			$location = self::getLocation($user, $filename, $timestamp);
+			$location = self::getLocation($user->getUID(), $filename, $timestamp);
 			if ($location === false) {
-				Server::get(LoggerInterface::class)->error('trash bin database inconsistent! ($user: ' . $user . ' $filename: ' . $filename . ', $timestamp: ' . $timestamp . ')', ['app' => 'files_trashbin']);
+				Server::get(LoggerInterface::class)->error('trash bin database inconsistent! ($user: ' . $user->getUID() . ' $filename: ' . $filename . ', $timestamp: ' . $timestamp . ')', ['app' => 'files_trashbin']);
 			} else {
 				// if location no longer exists, restore file in the root directory
 				if ($location !== '/'
@@ -510,8 +513,8 @@ public static function restore($file, $filename, $timestamp) {
 		$sourcePath = Filesystem::normalizePath($file);
 		$targetPath = Filesystem::normalizePath('/' . $location . '/' . $uniqueFilename);
 
-		$sourceNode = self::getNodeForPath($user, $sourcePath);
-		$targetNode = self::getNodeForPath($user, $targetPath, 'files');
+		$sourceNode = self::getNodeForPath($user->getUID(), $sourcePath);
+		$targetNode = self::getNodeForPath($user->getUID(), $targetPath, 'files');
 		$run = true;
 		$event = new BeforeNodeRestoredEvent($sourceNode, $targetNode, $run);
 		$dispatcher = Server::get(IEventDispatcher::class);
@@ -526,13 +529,13 @@ public static function restore($file, $filename, $timestamp) {
 		// handle the restore result
 		if ($restoreResult) {
 			$fakeRoot = $view->getRoot();
-			$view->chroot('/' . $user . '/files');
+			$view->chroot('/' . $user->getUID() . '/files');
 			$view->touch('/' . $location . '/' . $uniqueFilename, $mtime);
 			$view->chroot($fakeRoot);
 			Util::emitHook('\OCA\Files_Trashbin\Trashbin', 'post_restore', ['filePath' => $targetPath, 'trashPath' => $sourcePath]);
 
-			$sourceNode = self::getNodeForPath($user, $sourcePath);
-			$targetNode = self::getNodeForPath($user, $targetPath, 'files');
+			$sourceNode = self::getNodeForPath($user->getUID(), $sourcePath);
+			$targetNode = self::getNodeForPath($user->getUID(), $targetPath, 'files');
 			$event = new NodeRestoredEvent($sourceNode, $targetNode);
 			$dispatcher = Server::get(IEventDispatcher::class);
 			$dispatcher->dispatchTyped($event);
@@ -542,7 +545,7 @@ public static function restore($file, $filename, $timestamp) {
 			if ($timestamp) {
 				$query = Server::get(IDBConnection::class)->getQueryBuilder();
 				$query->delete('files_trash')
-					->where($query->expr()->eq('user', $query->createNamedParameter($user)))
+					->where($query->expr()->eq('user', $query->createNamedParameter($user->getUID())))
 					->andWhere($query->expr()->eq('id', $query->createNamedParameter($filename)))
 					->andWhere($query->expr()->eq('timestamp', $query->createNamedParameter($timestamp)));
 				$query->executeStatement();
@@ -567,7 +570,7 @@ public static function restore($file, $filename, $timestamp) {
 	 */
 	private static function restoreVersions(View $view, $file, $filename, $uniqueFilename, $location, $timestamp) {
 		if (Server::get(IAppManager::class)->isEnabledForUser('files_versions')) {
-			$user = OC_User::getUser();
+			$user = Server::get(IUserSession::class)->getUser()->getUID();
 			$rootView = new View('/');
 
 			$target = Filesystem::normalizePath('/' . $location . '/' . $uniqueFilename);
@@ -603,9 +606,9 @@ private static function restoreVersions(View $view, $file, $filename, $uniqueFil
 	 * delete all files from the trash
 	 */
 	public static function deleteAll() {
-		$user = OC_User::getUser();
-		$userRoot = \OC::$server->getUserFolder($user)->getParent();
-		$view = new View('/' . $user);
+		$user = Server::get(IUserSession::class)->getUser();
+		$userRoot = Server::get(IRootFolder::class)->getUserFolder($user->getUID())->getParent();
+		$view = new View('/' . $user->getUID());
 		$fileInfos = $view->getDirectoryContent('files_trashbin/files');
 
 		try {
@@ -634,7 +637,7 @@ public static function deleteAll() {
 
 		$query = Server::get(IDBConnection::class)->getQueryBuilder();
 		$query->delete('files_trash')
-			->where($query->expr()->eq('user', $query->createNamedParameter($user)));
+			->where($query->expr()->eq('user', $query->createNamedParameter($user->getUID())));
 		$query->executeStatement();
 
 		// Bulk PostDelete-Hook
@@ -751,8 +754,8 @@ private static function deleteVersions(View $view, $file, $filename, $timestamp,
 	 * @return bool true if file exists, otherwise false
 	 */
 	public static function file_exists($filename, $timestamp = null) {
-		$user = OC_User::getUser();
-		$view = new View('/' . $user);
+		$user = Server::get(IUserSession::class)->getUser();
+		$view = new View('/' . $user->getUID());
 
 		if ($timestamp) {
 			$filename = static::getTrashFilename($filename, $timestamp);
diff --git a/apps/files_trashbin/tests/TrashbinTest.php b/apps/files_trashbin/tests/TrashbinTest.php
index e34897330edd6..f7c6237cf1e5f 100644
--- a/apps/files_trashbin/tests/TrashbinTest.php
+++ b/apps/files_trashbin/tests/TrashbinTest.php
@@ -701,9 +701,9 @@ public static function loginHelper($user, $create = false) {
 		}
 
 		\OC_Util::tearDownFS();
-		\OC_User::setUserId('');
+		self::setUserId('');
 		Filesystem::tearDown();
-		\OC_User::setUserId($user);
+		self::setUserId($user);
 		\OC_Util::setupFS($user);
 		Server::get(IRootFolder::class)->getUserFolder($user);
 	}
diff --git a/apps/files_versions/lib/Storage.php b/apps/files_versions/lib/Storage.php
index fe9f91534fa01..70a19327b98db 100644
--- a/apps/files_versions/lib/Storage.php
+++ b/apps/files_versions/lib/Storage.php
@@ -15,7 +15,6 @@
 use OC\Files\Search\SearchQuery;
 use OC\Files\View;
 use OC\User\NoUserException;
-use OC_User;
 use OCA\Files_Sharing\SharedMount;
 use OCA\Files_Versions\AppInfo\Application;
 use OCA\Files_Versions\Command\Expire;
@@ -25,11 +24,11 @@
 use OCP\AppFramework\Db\DoesNotExistException;
 use OCP\Command\IBus;
 use OCP\EventDispatcher\IEventDispatcher;
-use OCP\Files;
 use OCP\Files\FileInfo;
 use OCP\Files\Folder;
 use OCP\Files\IMimeTypeDetector;
 use OCP\Files\IRootFolder;
+use OCP\Files\ISetupManager;
 use OCP\Files\Node;
 use OCP\Files\NotFoundException;
 use OCP\Files\NotPermittedException;
@@ -41,6 +40,7 @@
 use OCP\IURLGenerator;
 use OCP\IUser;
 use OCP\IUserManager;
+use OCP\IUserSession;
 use OCP\Lock\ILockingProvider;
 use OCP\Server;
 use OCP\Util;
@@ -93,10 +93,10 @@ public static function getUidAndFilename($filename) {
 		// to a remote user with a federated cloud ID we use the current logged-in
 		// user. We need a valid local user to create the versions
 		if (!$userManager->userExists($uid)) {
-			$uid = OC_User::getUser();
+			$uid = Server::get(IUserSession::class)->getUser()->getUID();
 		}
 		Filesystem::initMountPoints($uid);
-		if ($uid !== OC_User::getUser()) {
+		if ($uid !== Server::get(IUserSession::class)->getUser()->getUID()) {
 			$info = Filesystem::getFileInfo($filename);
 			$ownerView = new View('/' . $uid . '/files');
 			try {
@@ -853,7 +853,7 @@ public static function expire($filename, $uid) {
 				throw new NoUserException('Backends provided no user object for ' . $uid);
 			}
 
-			\OC_Util::setupFS($uid);
+			Server::get(ISetupManager::class)->setupForUser($user);
 
 			try {
 				if (!Filesystem::file_exists($filename)) {
diff --git a/apps/files_versions/tests/VersioningTest.php b/apps/files_versions/tests/VersioningTest.php
index fdc37016b5573..3022d5d1a173a 100644
--- a/apps/files_versions/tests/VersioningTest.php
+++ b/apps/files_versions/tests/VersioningTest.php
@@ -973,9 +973,9 @@ public static function loginHelper(string $user, bool $create = false) {
 		}
 
 		\OC_Util::tearDownFS();
-		\OC_User::setUserId('');
+		self::setUserId('');
 		Filesystem::tearDown();
-		\OC_User::setUserId($user);
+		self::setUserId($user);
 		\OC_Util::setupFS($user);
 		\OC::$server->getUserFolder($user);
 	}
diff --git a/apps/settings/lib/Settings/Personal/PersonalInfo.php b/apps/settings/lib/Settings/Personal/PersonalInfo.php
index 4f51b3a328367..1645f37760316 100644
--- a/apps/settings/lib/Settings/Personal/PersonalInfo.php
+++ b/apps/settings/lib/Settings/Personal/PersonalInfo.php
@@ -18,7 +18,9 @@
 use OCP\App\IAppManager;
 use OCP\AppFramework\Http\TemplateResponse;
 use OCP\AppFramework\Services\IInitialState;
+use OCP\Config\IUserConfig;
 use OCP\Files\FileInfo;
+use OCP\Files\ISetupManager;
 use OCP\IConfig;
 use OCP\IGroup;
 use OCP\IGroupManager;
@@ -36,7 +38,9 @@
 class PersonalInfo implements ISettings {
 
 	public function __construct(
+		private ?string $userId,
 		private IConfig $config,
+		private IUserConfig $userConfig,
 		private IUserManager $userManager,
 		private IGroupManager $groupManager,
 		private ITeamManager $teamManager,
@@ -47,6 +51,7 @@ public function __construct(
 		private IL10N $l,
 		private IInitialState $initialStateService,
 		private IManager $manager,
+		private ISetupManager $setupManager,
 	) {
 	}
 
@@ -60,12 +65,12 @@ public function getForm(): TemplateResponse {
 			$lookupServerUploadEnabled = $shareProvider->isLookupServerUploadEnabled();
 		}
 
-		$uid = \OC_User::getUser();
-		$user = $this->userManager->get($uid);
+
+		$user = $this->userManager->get($this->userId);
 		$account = $this->accountManager->getAccount($user);
 
 		// make sure FS is setup before querying storage related stuff...
-		\OC_Util::setupFS($user->getUID());
+		$this->setupManager->setupForUser($user);
 
 		$storageInfo = \OC_Helper::getStorageInfo('/');
 		if ($storageInfo['quota'] === FileInfo::SPACE_UNLIMITED) {
@@ -83,7 +88,7 @@ public function getForm(): TemplateResponse {
 		] + $messageParameters;
 
 		$personalInfoParameters = [
-			'userId' => $uid,
+			'userId' => $this->userId,
 			'avatar' => $this->getProperty($account, IAccountManager::PROPERTY_AVATAR),
 			'groups' => $this->getGroups($user),
 			'teams' => $this->getTeamMemberships($user),
@@ -109,8 +114,8 @@ public function getForm(): TemplateResponse {
 			'headline' => $this->getProperty($account, IAccountManager::PROPERTY_HEADLINE),
 			'biography' => $this->getProperty($account, IAccountManager::PROPERTY_BIOGRAPHY),
 			'birthdate' => $this->getProperty($account, IAccountManager::PROPERTY_BIRTHDATE),
-			'firstDayOfWeek' => $this->config->getUserValue($uid, 'core', AUserDataOCSController::USER_FIELD_FIRST_DAY_OF_WEEK),
-			'timezone' => $this->config->getUserValue($uid, 'core', 'timezone', ''),
+			'firstDayOfWeek' => $this->userConfig->getValueString($this->userId, 'core', AUserDataOCSController::USER_FIELD_FIRST_DAY_OF_WEEK),
+			'timezone' => $this->userConfig->getValueString($this->userId, 'core', 'timezone'),
 			'pronouns' => $this->getProperty($account, IAccountManager::PROPERTY_PRONOUNS),
 		];
 
@@ -252,7 +257,7 @@ private function getLanguageMap(IUser $user): array {
 
 		$uid = $user->getUID();
 
-		$userConfLang = $this->config->getUserValue($uid, 'core', 'lang', $this->l10nFactory->findLanguage());
+		$userConfLang = $this->userConfig->getValueString($uid, 'core', 'lang', $this->l10nFactory->findLanguage());
 		$languages = $this->l10nFactory->getLanguages();
 
 		// associate the user language with the proper array
@@ -284,8 +289,8 @@ private function getLocaleMap(IUser $user): array {
 		}
 
 		$uid = $user->getUID();
-		$userLang = $this->config->getUserValue($uid, 'core', 'lang', $this->l10nFactory->findLanguage());
-		$userLocaleString = $this->config->getUserValue($uid, 'core', 'locale', $this->l10nFactory->findLocale($userLang));
+		$userLang = $this->userConfig->getValueString($uid, 'core', 'lang', $this->l10nFactory->findLanguage());
+		$userLocaleString = $this->userConfig->getValueString($uid, 'core', 'locale', $this->l10nFactory->findLocale($userLang));
 		$localeCodes = $this->l10nFactory->findAvailableLocales();
 		$userLocale = array_filter($localeCodes, fn ($value) => $userLocaleString === $value['code']);
 
diff --git a/apps/settings/tests/Controller/AdminSettingsControllerTest.php b/apps/settings/tests/Controller/AdminSettingsControllerTest.php
index ce4f983bbbd79..41081448ba77b 100644
--- a/apps/settings/tests/Controller/AdminSettingsControllerTest.php
+++ b/apps/settings/tests/Controller/AdminSettingsControllerTest.php
@@ -69,7 +69,7 @@ protected function setUp(): void {
 		);
 
 		$user = Server::get(IUserManager::class)->createUser($this->adminUid, 'mylongrandompassword');
-		\OC_User::setUserId($user->getUID());
+		self::setUserId($user->getUID());
 		Server::get(IGroupManager::class)->createGroup('admin')->addUser($user);
 	}
 
@@ -77,7 +77,7 @@ protected function tearDown(): void {
 		Server::get(IUserManager::class)
 			->get($this->adminUid)
 			->delete();
-		\OC_User::setUserId(null);
+		self::setUserId(null);
 		Server::get(IUserSession::class)->setUser(null);
 
 		parent::tearDown();
diff --git a/apps/user_ldap/lib/Controller/RenewPasswordController.php b/apps/user_ldap/lib/Controller/RenewPasswordController.php
index d3e89a12d5621..cf5f12b923304 100644
--- a/apps/user_ldap/lib/Controller/RenewPasswordController.php
+++ b/apps/user_ldap/lib/Controller/RenewPasswordController.php
@@ -17,7 +17,6 @@
 use OCP\AppFramework\Services\IInitialState;
 use OCP\Config\IUserConfig;
 use OCP\HintException;
-use OCP\IConfig;
 use OCP\IL10N;
 use OCP\IRequest;
 use OCP\ISession;
@@ -31,7 +30,6 @@ public function __construct(
 		string $appName,
 		IRequest $request,
 		private IUserManager $userManager,
-		private IConfig $config,
 		private IUserConfig $userConfig,
 		protected IL10N $l10n,
 		private ISession $session,
@@ -98,17 +96,24 @@ public function tryRenewPassword(?string $user, string $oldPassword, ?string $ne
 		}
 
 		try {
-			if (!is_null($newPassword) && \OC_User::setPassword($user, $newPassword)) {
-				$this->session->set('loginMessages', [
-					[], [$this->l10n->t('Please login with the new password')]
-				]);
-				$this->userConfig->setValueBool($user, 'user_ldap', 'needsPasswordReset', false);
-				return new RedirectResponse($this->urlGenerator->linkToRoute('core.login.showLoginForm', $args));
-			} else {
-				$this->session->set('renewPasswordMessages', [
-					['internalexception'], []
-				]);
+			if (is_null($newPassword)) {
+				throw new HintException('The new password is null or empty');
 			}
+
+			$userObject = $this->userManager->get($user);
+			if ($userObject === null) {
+				throw new HintException('No user with the given user name exists');
+			}
+
+			if (!$userObject->setPassword($newPassword)) {
+				throw new HintException('Unable to change the password');
+			}
+
+			$this->session->set('loginMessages', [
+				[], [$this->l10n->t('Please login with the new password')]
+			]);
+			$this->userConfig->setValueBool($user, 'user_ldap', 'needsPasswordReset', false);
+			return new RedirectResponse($this->urlGenerator->linkToRoute('core.login.showLoginForm', $args));
 		} catch (HintException $e) {
 			$this->session->set('renewPasswordMessages', [
 				[], [$e->getHint()]
diff --git a/apps/user_ldap/tests/User_LDAPTest.php b/apps/user_ldap/tests/User_LDAPTest.php
index 4720b0a570935..eacf634618989 100644
--- a/apps/user_ldap/tests/User_LDAPTest.php
+++ b/apps/user_ldap/tests/User_LDAPTest.php
@@ -1238,9 +1238,11 @@ public function testSetPasswordInvalid(): void {
 			->method('get')
 			->willReturn($this->createMock(User::class));
 		$backend = new User_LDAP($this->access, $this->notificationManager, $this->pluginManager, $this->logger, $this->deletedUsersIndex);
-		Server::get(IUserManager::class)->registerBackend($backend);
-
-		$this->assertTrue(\OC_User::setPassword('roland', 'dt'));
+		$userManager = Server::get(IUserManager::class);
+		$userManager->registerBackend($backend);
+		$user = $userManager->get('roland');
+		$this->assertNotNull($user);
+		$this->assertTrue($user->setPassword('dt'));
 	}
 
 	public function testSetPasswordValid(): void {
@@ -1255,9 +1257,11 @@ public function testSetPasswordValid(): void {
 			->method('get')
 			->willReturn($this->createMock(User::class));
 
-		Server::get(IUserManager::class)->registerBackend($backend);
-
-		$this->assertTrue(\OC_User::setPassword('roland', 'dt12234$'));
+		$userManager = Server::get(IUserManager::class);
+		$userManager->registerBackend($backend);
+		$user = $userManager->get('roland');
+		$this->assertNotNull($user);
+		$this->assertTrue($user->setPassword('dt12234$'));
 	}
 
 	public function testSetPasswordValidDisabled(): void {
@@ -1267,9 +1271,11 @@ public function testSetPasswordValidDisabled(): void {
 
 		$this->prepareAccessForSetPassword(false);
 		$backend = new User_LDAP($this->access, $this->notificationManager, $this->pluginManager, $this->logger, $this->deletedUsersIndex);
-		Server::get(IUserManager::class)->registerBackend($backend);
-
-		$this->assertFalse(\OC_User::setPassword('roland', 'dt12234$'));
+		$userManager = Server::get(IUserManager::class);
+		$userManager->registerBackend($backend);
+		$user = $userManager->get('roland');
+		$this->assertNotNull($user);
+		$this->assertFalse($user->setPassword('dt12234$'));
 	}
 
 
diff --git a/build/psalm-baseline.xml b/build/psalm-baseline.xml
index e67cf7160eac6..3ee9658c883fe 100644
--- a/build/psalm-baseline.xml
+++ b/build/psalm-baseline.xml
@@ -485,6 +485,12 @@
     </InvalidNullableReturnType>
   </file>
   <file src="apps/dav/lib/Connector/Sabre/Auth.php">
+    <DeprecatedClass>
+      <code><![CDATA[\OC_User::handleApacheAuth()]]></code>
+    </DeprecatedClass>
+    <DeprecatedMethod>
+      <code><![CDATA[\OC_User::handleApacheAuth()]]></code>
+    </DeprecatedMethod>
     <LessSpecificReturnStatement>
       <code><![CDATA[$data]]></code>
     </LessSpecificReturnStatement>
@@ -1360,11 +1366,11 @@
   </file>
   <file src="apps/files_external/lib/Lib/Storage/SFTP.php">
     <InternalClass>
-      <code><![CDATA[new View('/' . $userId . '/files_external')]]></code>
+      <code><![CDATA[new View('/' . $user->getUID() . '/files_external')]]></code>
     </InternalClass>
     <InternalMethod>
       <code><![CDATA[getLocalFile]]></code>
-      <code><![CDATA[new View('/' . $userId . '/files_external')]]></code>
+      <code><![CDATA[new View('/' . $user->getUID() . '/files_external')]]></code>
       <code><![CDATA[put]]></code>
     </InternalMethod>
   </file>
@@ -1728,7 +1734,6 @@
 				'trashPath' => Filesystem::normalizePath(static::getTrashFilename($filename, $timestamp))])]]></code>
       <code><![CDATA[Util::emitHook('\OCA\Files_Trashbin\Trashbin', 'post_restore', ['filePath' => $targetPath, 'trashPath' => $sourcePath])]]></code>
       <code><![CDATA[getUserFolder]]></code>
-      <code><![CDATA[getUserFolder]]></code>
     </DeprecatedMethod>
     <InternalClass>
       <code><![CDATA[new View('/' . $owner)]]></code>
@@ -1740,9 +1745,9 @@
       <code><![CDATA[new View('/' . $user)]]></code>
       <code><![CDATA[new View('/' . $user)]]></code>
       <code><![CDATA[new View('/' . $user)]]></code>
-      <code><![CDATA[new View('/' . $user)]]></code>
-      <code><![CDATA[new View('/' . $user)]]></code>
-      <code><![CDATA[new View('/' . $user)]]></code>
+      <code><![CDATA[new View('/' . $user->getUID())]]></code>
+      <code><![CDATA[new View('/' . $user->getUID())]]></code>
+      <code><![CDATA[new View('/' . $user->getUID())]]></code>
       <code><![CDATA[new View('/')]]></code>
       <code><![CDATA[new View('/')]]></code>
       <code><![CDATA[new View('/')]]></code>
@@ -1805,9 +1810,9 @@
       <code><![CDATA[new View('/' . $user)]]></code>
       <code><![CDATA[new View('/' . $user)]]></code>
       <code><![CDATA[new View('/' . $user)]]></code>
-      <code><![CDATA[new View('/' . $user)]]></code>
-      <code><![CDATA[new View('/' . $user)]]></code>
-      <code><![CDATA[new View('/' . $user)]]></code>
+      <code><![CDATA[new View('/' . $user->getUID())]]></code>
+      <code><![CDATA[new View('/' . $user->getUID())]]></code>
+      <code><![CDATA[new View('/' . $user->getUID())]]></code>
       <code><![CDATA[new View('/')]]></code>
       <code><![CDATA[new View('/')]]></code>
       <code><![CDATA[new View('/')]]></code>
@@ -1928,9 +1933,6 @@
     </InvalidNullableReturnType>
   </file>
   <file src="apps/files_versions/lib/Storage.php">
-    <DeprecatedClass>
-      <code><![CDATA[\OC_Util::setupFS($uid)]]></code>
-    </DeprecatedClass>
     <DeprecatedInterface>
       <code><![CDATA[$bus]]></code>
     </DeprecatedInterface>
@@ -2204,20 +2206,10 @@
     </DeprecatedMethod>
   </file>
   <file src="apps/settings/lib/Settings/Personal/PersonalInfo.php">
-    <DeprecatedClass>
-      <code><![CDATA[\OC_Util::setupFS($user->getUID())]]></code>
-    </DeprecatedClass>
     <DeprecatedConstant>
       <code><![CDATA[IAccountManager::PROPERTY_TWITTER]]></code>
       <code><![CDATA[IAccountManager::PROPERTY_TWITTER]]></code>
     </DeprecatedConstant>
-    <DeprecatedMethod>
-      <code><![CDATA[getUserValue]]></code>
-      <code><![CDATA[getUserValue]]></code>
-      <code><![CDATA[getUserValue]]></code>
-      <code><![CDATA[getUserValue]]></code>
-      <code><![CDATA[getUserValue]]></code>
-    </DeprecatedMethod>
   </file>
   <file src="apps/settings/lib/Settings/Personal/Security/Authtokens.php">
     <DeprecatedClass>
@@ -3012,6 +3004,14 @@
       <code><![CDATA[private]]></code>
     </DeprecatedInterface>
   </file>
+  <file src="core/Controller/TwoFactorChallengeController.php">
+    <DeprecatedClass>
+      <code><![CDATA[OC_User::getLogoutUrl($this->urlGenerator)]]></code>
+    </DeprecatedClass>
+    <DeprecatedMethod>
+      <code><![CDATA[OC_User::getLogoutUrl($this->urlGenerator)]]></code>
+    </DeprecatedMethod>
+  </file>
   <file src="core/Controller/UnifiedSearchController.php">
     <DeprecatedInterface>
       <code><![CDATA[private]]></code>
@@ -3899,9 +3899,12 @@
     </UndefinedInterfaceMethod>
   </file>
   <file src="lib/private/legacy/OC_User.php">
-    <UndefinedClass>
-      <code><![CDATA[\Test\Util\User\Dummy]]></code>
-    </UndefinedClass>
+    <UndefinedInterfaceMethod>
+      <code><![CDATA[createRememberMeToken]]></code>
+      <code><![CDATA[createSessionToken]]></code>
+      <code><![CDATA[getSession]]></code>
+      <code><![CDATA[setLoginName]]></code>
+    </UndefinedInterfaceMethod>
   </file>
   <file src="lib/public/AppFramework/Http/Response.php">
     <LessSpecificReturnStatement>
diff --git a/core/ajax/update.php b/core/ajax/update.php
index 0a882929537d9..e412acbddc932 100644
--- a/core/ajax/update.php
+++ b/core/ajax/update.php
@@ -21,6 +21,7 @@
 use OCP\IConfig;
 use OCP\IEventSourceFactory;
 use OCP\IL10N;
+use OCP\IUserSession;
 use OCP\L10N\IFactory;
 use OCP\Server;
 use OCP\Util;
@@ -51,7 +52,7 @@
 
 	// if a user is currently logged in, their session must be ignored to
 	// avoid side effects
-	\OC_User::setIncognitoMode(true);
+	Server::get(IUserSession::class)->setIncognitoMode(true);
 
 	$config = Server::get(IConfig::class);
 	$updater = Server::get(Updater::class);
diff --git a/lib/base.php b/lib/base.php
index a11334c50cfd7..cf947d8e57bb3 100644
--- a/lib/base.php
+++ b/lib/base.php
@@ -834,7 +834,7 @@ public static function init(): void {
 			OC_User::setupBackends();
 		} else {
 			// Run upgrades in incognito mode
-			OC_User::setIncognitoMode(true);
+			Server::get(IUserSession::class)->setIncognitoMode(true);
 		}
 		$eventLogger->end('setup_backends');
 
diff --git a/lib/private/AppFramework/DependencyInjection/DIContainer.php b/lib/private/AppFramework/DependencyInjection/DIContainer.php
index 7527d2495863b..4df0c1c99b492 100644
--- a/lib/private/AppFramework/DependencyInjection/DIContainer.php
+++ b/lib/private/AppFramework/DependencyInjection/DIContainer.php
@@ -287,15 +287,6 @@ public function isLoggedIn() {
 		return Server::get(IUserSession::class)->isLoggedIn();
 	}
 
-	/**
-	 * @deprecated 12.0.0 use IGroupManager->isAdmin($userId)
-	 * @return boolean
-	 */
-	public function isAdminUser() {
-		$uid = $this->getUserId();
-		return \OC_User::isAdminUser($uid);
-	}
-
 	private function getUserId(): string {
 		return $this->getServer()->get(Session::class)->getSession()->get('user_id');
 	}
diff --git a/lib/private/DirectEditing/Manager.php b/lib/private/DirectEditing/Manager.php
index bcb69163dbbab..709bf0329ef5f 100644
--- a/lib/private/DirectEditing/Manager.php
+++ b/lib/private/DirectEditing/Manager.php
@@ -25,6 +25,8 @@
 use OCP\Files\NotFoundException;
 use OCP\IDBConnection;
 use OCP\IL10N;
+use OCP\ISession;
+use OCP\IUserManager;
 use OCP\IUserSession;
 use OCP\L10N\IFactory;
 use OCP\Security\ISecureRandom;
@@ -239,8 +241,14 @@ public function accessToken(string $token): bool {
 		return $result !== 0;
 	}
 
-	public function invokeTokenScope($userId): void {
-		\OC_User::setUserId($userId);
+	public function invokeTokenScope(string $userId): void {
+		$userSession = Server::get(IUserSession::class);
+		$userManager = Server::get(IUserManager::class);
+		if ($user = $userManager->get($userId)) {
+			$userSession->setUser($user);
+		} else {
+			Server::get(ISession::class)->set('user_id', $userId);
+		}
 	}
 
 	public function revertTokenScope(): void {
diff --git a/lib/private/Files/View.php b/lib/private/Files/View.php
index 21265b7d0483b..605b952e077bf 100644
--- a/lib/private/Files/View.php
+++ b/lib/private/Files/View.php
@@ -1427,6 +1427,7 @@ public function getFileInfo($path, $includeMountPoints = true) {
 		$path = Filesystem::normalizePath($this->fakeRoot . '/' . $path);
 
 		$mount = Filesystem::getMountManager()->find($path);
+		/** @var ?Storage $storage */
 		$storage = $mount->getStorage();
 		$internalPath = $mount->getInternalPath($path);
 		if ($storage) {
@@ -1502,6 +1503,7 @@ public function getDirectoryContent(string $directory, ?string $mimeTypeFilter =
 		$path = $this->getAbsolutePath($directory);
 		$path = Filesystem::normalizePath($path);
 		$mount = $this->getMount($directory);
+		/** @var ?Storage $storage */
 		$storage = $mount->getStorage();
 		$internalPath = $mount->getInternalPath($path);
 		if (!$storage) {
diff --git a/lib/private/User/Session.php b/lib/private/User/Session.php
index 811c5ba4bc326..05a4d31bf0f81 100644
--- a/lib/private/User/Session.php
+++ b/lib/private/User/Session.php
@@ -19,7 +19,6 @@
 use OC\Hooks\PublicEmitter;
 use OC\Http\CookieHelper;
 use OC\Security\CSRF\CsrfTokenManager;
-use OC_User;
 use OC_Util;
 use OCA\DAV\Connector\Sabre\Auth;
 use OCP\AppFramework\Db\TTransactional;
@@ -73,6 +72,8 @@ class Session implements IUserSession, Emitter {
 	/** @var User $activeUser */
 	protected $activeUser;
 
+	private bool $incognitoMode = false;
+
 	public function __construct(
 		private Manager $manager,
 		private ISession $session,
@@ -170,10 +171,10 @@ public function setVolatileActiveUser(?IUser $user): void {
 	 *
 	 * @return IUser|null Current user, otherwise null
 	 */
-	public function getUser() {
+	public function getUser(): ?IUser {
 		// FIXME: This is a quick'n dirty work-around for the incognito mode as
 		// described at https://github.com/owncloud/core/pull/12912#issuecomment-67391155
-		if (OC_User::isIncognitoMode()) {
+		if ($this->isIncognitoMode()) {
 			return null;
 		}
 		if (is_null($this->activeUser)) {
@@ -1065,4 +1066,16 @@ public function updateSessionTokenPassword($password) {
 	public function updateTokens(string $uid, string $password) {
 		$this->tokenProvider->updatePasswords($uid, $password);
 	}
+
+	public function isIncognitoMode(): bool {
+		return $this->incognitoMode;
+	}
+
+	/**
+	 * Set whether the current session is in incognito mode or not.
+	 * @since 34.0.0
+	 */
+	public function setIncognitoMode(bool $incognitoMode): void {
+		$this->incognitoMode = $incognitoMode;
+	}
 }
diff --git a/lib/private/legacy/OC_User.php b/lib/private/legacy/OC_User.php
index ddd426da942e4..87315d55d530d 100644
--- a/lib/private/legacy/OC_User.php
+++ b/lib/private/legacy/OC_User.php
@@ -7,15 +7,17 @@
  */
 use OC\Authentication\Token\IProvider;
 use OC\SystemConfig;
-use OC\User\Database;
 use OC\User\DisabledUserException;
 use OC\User\Session;
+use OCP\App\IAppManager;
 use OCP\Authentication\Exceptions\InvalidTokenException;
 use OCP\Authentication\Exceptions\WipeTokenException;
 use OCP\Authentication\IApacheBackend;
 use OCP\Authentication\IProvideUserSecretBackend;
 use OCP\Authentication\Token\IToken;
 use OCP\EventDispatcher\IEventDispatcher;
+use OCP\Files\IRootFolder;
+use OCP\Files\ISetupManager;
 use OCP\IGroupManager;
 use OCP\IRequest;
 use OCP\ISession;
@@ -23,12 +25,12 @@
 use OCP\IUser;
 use OCP\IUserManager;
 use OCP\IUserSession;
+use OCP\L10N\IFactory;
 use OCP\Server;
 use OCP\Session\Exceptions\SessionNotAvailableException;
 use OCP\User\Backend\ICustomLogout;
 use OCP\User\Events\BeforeUserLoggedInEvent;
 use OCP\User\Events\UserLoggedInEvent;
-use OCP\UserInterface;
 use OCP\Util;
 use Psr\Log\LoggerInterface;
 
@@ -49,70 +51,28 @@
  *   pre_login(&run, uid, password)
  *   post_login(uid)
  *   logout()
+ *
+ * @deprecated 34.0.0
  */
 class OC_User {
 	private static $_setupedBackends = [];
 
-	// bool, stores if a user want to access a resource anonymously, e.g if they open a public link
-	private static $incognitoMode = false;
-
 	/**
-	 * Adds the backend to the list of used backends
-	 *
-	 * @param string|UserInterface $backend default: database The backend to use for user management
-	 * @return bool
-	 * @deprecated 32.0.0 Use IUserManager::registerBackend instead
+	 * Set up the configured backends in config.php.
 	 *
-	 * Set the User Authentication Module
+	 * @suppress PhanDeprecatedFunction
+	 * @deprecated 34.0.0 This is internal, not to be used by apps
 	 */
-	public static function useBackend($backend = 'database') {
-		if ($backend instanceof UserInterface) {
-			Server::get(IUserManager::class)->registerBackend($backend);
-		} else {
-			// You'll never know what happens
-			if ($backend === null || !is_string($backend)) {
-				$backend = 'database';
-			}
-
-			// Load backend
-			switch ($backend) {
-				case 'database':
-				case 'mysql':
-				case 'sqlite':
-					Server::get(LoggerInterface::class)->debug('Adding user backend ' . $backend . '.', ['app' => 'core']);
-					Server::get(IUserManager::class)->registerBackend(new Database());
-					break;
-				case 'dummy':
-					Server::get(IUserManager::class)->registerBackend(new \Test\Util\User\Dummy());
-					break;
-				default:
-					Server::get(LoggerInterface::class)->debug('Adding default user backend ' . $backend . '.', ['app' => 'core']);
-					$className = 'OC_USER_' . strtoupper($backend);
-					Server::get(IUserManager::class)->registerBackend(new $className());
-					break;
-			}
+	public static function setupBackends(): void {
+		if (!Server::get(SystemConfig::class)->getValue('installed', false)) {
+			return;
 		}
-		return true;
-	}
+		Server::get(IAppManager::class)->loadApps(['prelogin']);
 
-	/**
-	 * remove all used backends
-	 * @deprecated 32.0.0 Use IUserManager::clearBackends instead
-	 */
-	public static function clearBackends() {
-		Server::get(IUserManager::class)->clearBackends();
-	}
-
-	/**
-	 * setup the configured backends in config.php
-	 * @suppress PhanDeprecatedFunction
-	 */
-	public static function setupBackends() {
-		OC_App::loadApps(['prelogin']);
 		$backends = Server::get(SystemConfig::class)->getValue('user_backends', []);
 		if (isset($backends['default']) && !$backends['default']) {
 			// clear default backends
-			self::clearBackends();
+			Server::get(IUserManager::class)->clearBackends();
 		}
 		foreach ($backends as $i => $config) {
 			if (!is_array($config)) {
@@ -120,104 +80,111 @@ public static function setupBackends() {
 			}
 			$class = $config['class'];
 			$arguments = $config['arguments'];
-			if (class_exists($class)) {
-				if (!in_array($i, self::$_setupedBackends)) {
-					// make a reflection object
-					$reflectionObj = new ReflectionClass($class);
-
-					// use Reflection to create a new instance, using the $args
-					$backend = $reflectionObj->newInstanceArgs($arguments);
-					self::useBackend($backend);
-					self::$_setupedBackends[] = $i;
-				} else {
-					Server::get(LoggerInterface::class)->debug('User backend ' . $class . ' already initialized.', ['app' => 'core']);
-				}
-			} else {
+			if (!class_exists($class)) {
 				Server::get(LoggerInterface::class)->error('User backend ' . $class . ' not found.', ['app' => 'core']);
 			}
+			if (in_array($i, self::$_setupedBackends)) {
+				Server::get(LoggerInterface::class)->debug('User backend ' . $class . ' already initialized.', ['app' => 'core']);
+			}
+			// make a reflection object
+			$reflectionObj = new ReflectionClass($class);
+
+			// use Reflection to create a new instance, using the $args
+			$backend = $reflectionObj->newInstanceArgs($arguments);
+			Server::get(IUserManager::class)->registerBackend($backend);
+			self::$_setupedBackends[] = $i;
 		}
 	}
 
 	/**
-	 * Try to login a user, assuming authentication
+	 * Try to log in a user, assuming authentication
 	 * has already happened (e.g. via Single Sign On).
 	 *
 	 * Log in a user and regenerate a new session.
+	 *
+	 * @deprecated 34.0.0 This is internal, not to be used by apps
 	 */
 	public static function loginWithApache(IApacheBackend $backend): bool {
 		$uid = $backend->getCurrentUserId();
 		$run = true;
 		OC_Hook::emit('OC_User', 'pre_login', ['run' => &$run, 'uid' => $uid, 'backend' => $backend]);
 
-		if ($uid) {
-			if (self::getUser() !== $uid) {
-				self::setUserId($uid);
-				/** @var Session $userSession */
-				$userSession = Server::get(IUserSession::class);
+		if (!$uid) {
+			return false;
+		}
 
-				/** @var IEventDispatcher $dispatcher */
-				$dispatcher = Server::get(IEventDispatcher::class);
+		$userSession = Server::get(IUserSession::class);
+		$userManager = Server::get(IUserManager::class);
+		$dispatcher = Server::get(IEventDispatcher::class);
 
-				if ($userSession->getUser() && !$userSession->getUser()->isEnabled()) {
-					$message = \OC::$server->getL10N('lib')->t('Account disabled');
-					throw new DisabledUserException($message);
-				}
-				$userSession->setLoginName($uid);
-				$request = Server::get(IRequest::class);
-				$password = null;
-				if ($backend instanceof IProvideUserSecretBackend) {
-					$password = $backend->getCurrentUserSecret();
-				}
+		$user = $userSession->getUser();
+		if ($user && $user->getUID() === $uid) {
+			return true;
+		}
 
-				/** @var IEventDispatcher $dispatcher */
-				$dispatcher->dispatchTyped(new BeforeUserLoggedInEvent($uid, $password, $backend));
-
-				$userSession->createSessionToken($request, $uid, $uid, $password);
-				$userSession->createRememberMeToken($userSession->getUser());
-
-				if (empty($password)) {
-					$tokenProvider = Server::get(IProvider::class);
-					try {
-						$token = $tokenProvider->getToken($userSession->getSession()->getId());
-						$token->setScope([
-							IToken::SCOPE_SKIP_PASSWORD_VALIDATION => true,
-							IToken::SCOPE_FILESYSTEM => true,
-						]);
-						$tokenProvider->updateToken($token);
-					} catch (InvalidTokenException|WipeTokenException|SessionNotAvailableException) {
-						// swallow the exceptions as we do not deal with them here
-						// simply skip updating the token when is it missing
-					}
-				}
+		if ($user = $userManager->get($uid)) {
+			$userSession->setUser($user);
+		} else {
+			Server::get(ISession::class)->set('user_id', $uid);
+		}
 
-				// setup the filesystem
-				OC_Util::setupFS($uid);
-				// first call the post_login hooks, the login-process needs to be
-				// completed before we can safely create the users folder.
-				// For example encryption needs to initialize the users keys first
-				// before we can create the user folder with the skeleton files
-				OC_Hook::emit(
-					'OC_User',
-					'post_login',
-					[
-						'uid' => $uid,
-						'password' => $password,
-						'isTokenLogin' => false,
-					]
-				);
-				$dispatcher->dispatchTyped(new UserLoggedInEvent(
-					Server::get(IUserManager::class)->get($uid),
-					$uid,
-					null,
-					false)
-				);
-
-				//trigger creation of user home and /files folder
-				\OC::$server->getUserFolder($uid);
+		if (!$user->isEnabled()) {
+			$message = Server::get(IFactory::class)->get('lib')->t('Account disabled');
+			throw new DisabledUserException($message);
+		}
+
+		$userSession->setLoginName($uid);
+		$request = Server::get(IRequest::class);
+		$password = null;
+		if ($backend instanceof IProvideUserSecretBackend) {
+			$password = $backend->getCurrentUserSecret();
+		}
+
+		$dispatcher->dispatchTyped(new BeforeUserLoggedInEvent($uid, $password, $backend));
+
+		$userSession->createSessionToken($request, $uid, $uid, $password);
+		$userSession->createRememberMeToken($user);
+
+		if (empty($password)) {
+			$tokenProvider = Server::get(IProvider::class);
+			try {
+				$token = $tokenProvider->getToken($userSession->getSession()->getId());
+				$token->setScope([
+					IToken::SCOPE_SKIP_PASSWORD_VALIDATION => true,
+					IToken::SCOPE_FILESYSTEM => true,
+				]);
+				$tokenProvider->updateToken($token);
+			} catch (InvalidTokenException|WipeTokenException|SessionNotAvailableException) {
+				// swallow the exceptions as we do not deal with them here
+				// simply skip updating the token when is it missing
 			}
-			return true;
 		}
-		return false;
+
+		// Set up the filesystem
+		Server::get(ISetupManager::class)->setupForUser($user);
+		// first call the post_login hooks, the login-process needs to be
+		// completed before we can safely create the user's folder.
+		// For example encryption needs to initialize the users keys first
+		// before we can create the user folder with the skeleton files
+		OC_Hook::emit(
+			'OC_User',
+			'post_login',
+			[
+				'uid' => $uid,
+				'password' => $password,
+				'isTokenLogin' => false,
+			]
+		);
+		$dispatcher->dispatchTyped(new UserLoggedInEvent(
+			Server::get(IUserManager::class)->get($uid),
+			$uid,
+			null,
+			false)
+		);
+
+		// trigger creation of user home and /files folder
+		Server::get(IRootFolder::class)->getUserFolder($uid);
+		return true;
 	}
 
 	/**
@@ -227,13 +194,15 @@ public static function loginWithApache(IApacheBackend $backend): bool {
 	 *                   true: authenticated
 	 *                   false: not authenticated
 	 *                   null: not handled / no backend available
+	 *
+	 * @deprecated 34.0.0 This is internal, not to be used by apps
 	 */
 	public static function handleApacheAuth(): ?bool {
 		$backend = self::findFirstActiveUsedBackend();
 		if ($backend) {
-			OC_App::loadApps();
+			Server::get(IAppManager::class)->loadApps();
 
-			//setup extra user backends
+			// set up extra user backends
 			self::setupBackends();
 			/** @var Session $session */
 			$session = Server::get(IUserSession::class);
@@ -248,6 +217,7 @@ public static function handleApacheAuth(): ?bool {
 
 	/**
 	 * Sets user id for session and triggers emit
+	 * @deprecated 34.0.0 Use TestCase::setUserId in your test instead
 	 */
 	public static function setUserId(?string $uid): void {
 		$userSession = Server::get(IUserSession::class);
@@ -261,20 +231,23 @@ public static function setUserId(?string $uid): void {
 
 	/**
 	 * Set incognito mode, e.g. if a user wants to open a public link
+	 * @deprecated 34.0.0 Use IUserSession::setIncognitoMode
 	 */
 	public static function setIncognitoMode(bool $status): void {
-		self::$incognitoMode = $status;
+		Server::get(IUserSession::class)->setIncognitoMode($status);
 	}
 
 	/**
 	 * Get incognito mode status
+	 * @deprecated 34.0.0 Use IUserSession::isIncognitoMode
 	 */
 	public static function isIncognitoMode(): bool {
-		return self::$incognitoMode;
+		return Server::get(IUserSession::class)->isIncognitoMode();
 	}
 
 	/**
 	 * Returns the current logout URL valid for the currently logged-in user
+	 * @deprecated 34.0.0
 	 */
 	public static function getLogoutUrl(IURLGenerator $urlGenerator): string {
 		$backend = self::findFirstActiveUsedBackend();
@@ -300,11 +273,12 @@ public static function getLogoutUrl(IURLGenerator $urlGenerator): string {
 	 * Check if the user is an admin user
 	 *
 	 * @param string $uid uid of the admin
+	 * @deprecated 34.0.0 Use IGroupManager::isAdmin instead
 	 */
 	public static function isAdminUser(string $uid): bool {
 		$user = Server::get(IUserManager::class)->get($uid);
 		$isAdmin = $user && Server::get(IGroupManager::class)->isAdmin($user->getUID());
-		return $isAdmin && self::$incognitoMode === false;
+		return $isAdmin && !Server::get(IUserSession::class)->isIncognitoMode();
 	}
 
 
@@ -312,10 +286,11 @@ public static function isAdminUser(string $uid): bool {
 	 * get the user id of the user currently logged in.
 	 *
 	 * @return string|false uid or false
+	 * @deprecated 34.0.0 Use IUserSession::getUser instead
 	 */
 	public static function getUser(): string|false {
 		$uid = Server::get(ISession::class)?->get('user_id');
-		if (!is_null($uid) && self::$incognitoMode === false) {
+		if (!is_null($uid) && !Server::get(IUserSession::class)->isIncognitoMode()) {
 			return $uid;
 		} else {
 			return false;
@@ -330,6 +305,7 @@ public static function getUser(): string|false {
 	 * @param string $recoveryPassword for the encryption app to reset encryption keys
 	 *
 	 * Change the password of a user
+	 * @deprecated 34.0.0 Use IUserManager::setPassword instead
 	 */
 	public static function setPassword(string $uid, string $password, ?string $recoveryPassword = null): bool {
 		$user = Server::get(IUserManager::class)->get($uid);
diff --git a/lib/private/legacy/OC_Util.php b/lib/private/legacy/OC_Util.php
index b3b0f4e3e20ca..ceec426b21cc7 100644
--- a/lib/private/legacy/OC_Util.php
+++ b/lib/private/legacy/OC_Util.php
@@ -572,7 +572,11 @@ public static function checkLoggedIn(): void {
 	 */
 	public static function checkAdminUser(): void {
 		self::checkLoggedIn();
-		if (!OC_User::isAdminUser(OC_User::getUser())) {
+
+		$user = Server::get(IUserSession::class)->getUser();
+		$isAdmin = $user && Server::get(IGroupManager::class)->isAdmin($user->getUID());
+
+		if (!$isAdmin) {
 			header('Location: ' . Util::linkToAbsolute('', 'index.php'));
 			exit();
 		}
diff --git a/lib/public/IUserSession.php b/lib/public/IUserSession.php
index 42cc437aabae1..cfc23715d4b26 100644
--- a/lib/public/IUserSession.php
+++ b/lib/public/IUserSession.php
@@ -92,4 +92,16 @@ public function getImpersonatingUserID(): ?string;
 	 * @since 18.0.0
 	 */
 	public function setImpersonatingUserID(bool $useCurrentUser = true): void;
+
+	/**
+	 * Returns whether the current session is in incognito mode.
+	 * @since 34.0.0
+	 */
+	public function isIncognitoMode(): bool;
+
+	/**
+	 * Set whether the current session is in incognito mode or not.
+	 * @since 34.0.0
+	 */
+	public function setIncognitoMode(bool $incognitoMode): void;
 }
diff --git a/public.php b/public.php
index 8ae6deff20305..b190a61333a10 100644
--- a/public.php
+++ b/public.php
@@ -15,6 +15,7 @@
 use OCP\App\IAppManager;
 use OCP\IConfig;
 use OCP\IRequest;
+use OCP\IUserSession;
 use OCP\Server;
 use OCP\Template\ITemplateManager;
 use OCP\Util;
@@ -84,7 +85,8 @@ function resolveService(string $service): string {
 
 	// Load the app
 	$appManager->loadApp($app);
-	OC_User::setIncognitoMode(true);
+	$userSession = Server::get(IUserSession::class);
+	$userSession->setIncognitoMode(true);
 
 	$baseuri = OC::$WEBROOT . '/public.php/' . $service . '/';
 	require_once $file;
diff --git a/tests/lib/AppFramework/DependencyInjection/DIContainerTest.php b/tests/lib/AppFramework/DependencyInjection/DIContainerTest.php
index 4fbe5c8307ba4..4f1a583808394 100644
--- a/tests/lib/AppFramework/DependencyInjection/DIContainerTest.php
+++ b/tests/lib/AppFramework/DependencyInjection/DIContainerTest.php
@@ -20,18 +20,14 @@
 use OCP\AppFramework\QueryException;
 use OCP\IConfig;
 use OCP\IRequestId;
-use PHPUnit\Framework\MockObject\MockObject;
 
 #[\PHPUnit\Framework\Attributes\Group('DB')]
 class DIContainerTest extends \Test\TestCase {
-	private DIContainer&MockObject $container;
+	private DIContainer $container;
 
 	protected function setUp(): void {
 		parent::setUp();
-		$this->container = $this->getMockBuilder(DIContainer::class)
-			->onlyMethods(['isAdminUser'])
-			->setConstructorArgs(['name'])
-			->getMock();
+		$this->container = new DIContainer('name');
 	}
 
 
diff --git a/tests/lib/AppTest.php b/tests/lib/AppTest.php
index 83944ce2f7eb2..0b43e7fffa4b8 100644
--- a/tests/lib/AppTest.php
+++ b/tests/lib/AppTest.php
@@ -199,7 +199,7 @@ public function testEnabledApps($user, $expectedApps, $forceAll): void {
 		$group2->addUser($user2);
 		$group2->addUser($user3);
 
-		\OC_User::setUserId($user);
+		self::setUserId($user);
 
 		$this->setupAppConfigMock()->expects($this->once())
 			->method('searchValues')
@@ -217,7 +217,7 @@ public function testEnabledApps($user, $expectedApps, $forceAll): void {
 		$apps = \OC_App::getEnabledApps(false, $forceAll);
 
 		$this->restoreAppConfig();
-		\OC_User::setUserId(null);
+		self::setUserId(null);
 
 		$user1->delete();
 		$user2->delete();
@@ -237,7 +237,7 @@ public function testEnabledAppsCache(): void {
 		$userManager = Server::get(IUserManager::class);
 		$user1 = $userManager->createUser(self::TEST_USER1, 'NotAnEasyPassword123456+');
 
-		\OC_User::setUserId(self::TEST_USER1);
+		self::setUserId(self::TEST_USER1);
 
 		$this->setupAppConfigMock()->expects($this->once())
 			->method('searchValues')
@@ -256,7 +256,7 @@ public function testEnabledAppsCache(): void {
 		$this->assertEquals(['files', 'app3', 'cloud_federation_api', 'dav', 'federatedfilesharing', 'lookup_server_connector', 'oauth2', 'profile', 'provisioning_api', 'settings', 'theming', 'twofactor_backupcodes', 'viewer', 'workflowengine'], $apps);
 
 		$this->restoreAppConfig();
-		\OC_User::setUserId(null);
+		self::setUserId(null);
 
 		$user1->delete();
 	}
diff --git a/tests/lib/Cache/FileCacheTest.php b/tests/lib/Cache/FileCacheTest.php
index 9ba19553cf134..98ef96fa033de 100644
--- a/tests/lib/Cache/FileCacheTest.php
+++ b/tests/lib/Cache/FileCacheTest.php
@@ -59,7 +59,7 @@ protected function setUp(): void {
 		$this->createUser('test', 'test');
 
 		$this->user = \OC_User::getUser();
-		\OC_User::setUserId('test');
+		self::setUserId('test');
 
 		//clear all proxies and hooks so we can do clean testing
 		\OC_Hook::clear('OC_Filesystem');
@@ -86,7 +86,7 @@ protected function tearDown(): void {
 			$this->instance->remove('hack', 'hack');
 		}
 
-		\OC_User::setUserId($this->user);
+		self::setUserId($this->user);
 
 		if ($this->instance) {
 			$this->instance->clear();
diff --git a/tests/lib/Files/ViewTest.php b/tests/lib/Files/ViewTest.php
index 94d55b4e9c411..1ad42ae76bfa3 100644
--- a/tests/lib/Files/ViewTest.php
+++ b/tests/lib/Files/ViewTest.php
@@ -147,7 +147,7 @@ protected function setUp(): void {
 	}
 
 	protected function tearDown(): void {
-		\OC_User::setUserId($this->user);
+		self::setUserId($this->user);
 		foreach ($this->storages as $storage) {
 			$cache = $storage->getCache();
 			$ids = $cache->getAll();
diff --git a/tests/lib/HelperStorageTest.php b/tests/lib/HelperStorageTest.php
index 914936c9657ad..2f0bf31e5e9bf 100644
--- a/tests/lib/HelperStorageTest.php
+++ b/tests/lib/HelperStorageTest.php
@@ -40,7 +40,7 @@ protected function setUp(): void {
 		$this->savedQuotaIncludeExternalStorage = $this->getIncludeExternalStorage();
 
 		Filesystem::tearDown();
-		\OC_User::setUserId($this->user);
+		self::setUserId($this->user);
 		Filesystem::init($this->user, '/' . $this->user . '/files');
 
 		/** @var IMountManager $manager */
@@ -60,7 +60,7 @@ protected function tearDown(): void {
 		}
 		Filesystem::tearDown();
 
-		\OC_User::setUserId('');
+		self::setUserId('');
 		Server::get(IConfig::class)->deleteAllUserValues($this->user);
 
 		parent::tearDown();
diff --git a/tests/lib/Security/CertificateManagerTest.php b/tests/lib/Security/CertificateManagerTest.php
index 04262b62818cb..2dcd83d03f0a6 100644
--- a/tests/lib/Security/CertificateManagerTest.php
+++ b/tests/lib/Security/CertificateManagerTest.php
@@ -45,7 +45,7 @@ protected function setUp(): void {
 		$this->registerMount($this->username, $storage, '/' . $this->username . '/');
 
 		\OC_Util::tearDownFS();
-		\OC_User::setUserId($this->username);
+		self::setUserId($this->username);
 		Filesystem::tearDown();
 		\OC_Util::setupFS($this->username);
 
diff --git a/tests/lib/TagsTest.php b/tests/lib/TagsTest.php
index 1827870ca6e21..1d580d1f2bf12 100644
--- a/tests/lib/TagsTest.php
+++ b/tests/lib/TagsTest.php
@@ -46,7 +46,7 @@ protected function setUp(): void {
 		Server::get(IUserManager::class)->registerBackend(new \Test\Util\User\Dummy());
 		$userId = $this->getUniqueID('user_');
 		Server::get(IUserManager::class)->createUser($userId, 'pass');
-		\OC_User::setUserId($userId);
+		self::setUserId($userId);
 		$this->user = $this->createMock(IUser::class);
 		$this->user->method('getUID')
 			->willReturn($userId);
diff --git a/tests/lib/TestCase.php b/tests/lib/TestCase.php
index c40c05b3de773..92e53c37b5cc8 100644
--- a/tests/lib/TestCase.php
+++ b/tests/lib/TestCase.php
@@ -29,6 +29,7 @@
 use OCP\Files\IRootFolder;
 use OCP\IConfig;
 use OCP\IDBConnection;
+use OCP\ISession;
 use OCP\IUserManager;
 use OCP\IUserSession;
 use OCP\Lock\ILockingProvider;
@@ -426,7 +427,7 @@ protected static function tearDownAfterClassCleanStrayLocks(): void {
 	protected static function loginAsUser(string $user = ''): void {
 		self::logout();
 		Filesystem::tearDown();
-		\OC_User::setUserId($user);
+		self::setUserId($user);
 		$userManager = Server::get(IUserManager::class);
 		$setupManager = Server::get(SetupManager::class);
 		$userObject = $userManager->get($user);
@@ -533,4 +534,15 @@ protected function IsDatabaseAccessAllowed(): bool {
 		$annotations = $this->getGroupAnnotations();
 		return in_array('DB', $annotations) || in_array('SLOWDB', $annotations);
 	}
+
+
+	protected static function setUserId(?string $uid): void {
+		$userSession = Server::get(IUserSession::class);
+		$userManager = Server::get(IUserManager::class);
+		if ($user = $userManager->get($uid)) {
+			$userSession->setUser($user);
+		} else {
+			Server::get(ISession::class)->set('user_id', $uid);
+		}
+	}
 }
diff --git a/tests/lib/Traits/EncryptionTrait.php b/tests/lib/Traits/EncryptionTrait.php
index 2dc9213ff2431..a5f7f91a10ae4 100644
--- a/tests/lib/Traits/EncryptionTrait.php
+++ b/tests/lib/Traits/EncryptionTrait.php
@@ -17,6 +17,7 @@
 use OCA\Encryption\Users\Setup;
 use OCP\App\IAppManager;
 use OCP\Encryption\IManager;
+use OCP\Files\IRootFolder;
 use OCP\IConfig;
 use OCP\IUserManager;
 use OCP\IUserSession;
@@ -53,19 +54,21 @@ abstract protected static function assertTrue($condition, string $message = ''):
 	 */
 	private $encryptionApp;
 
-	protected function loginWithEncryption($user = '') {
-		\OC_Util::tearDownFS();
-		\OC_User::setUserId('');
+	protected function loginWithEncryption(string $user = ''): void {
+		$this->setupManager->tearDown();
+		self::setUserId('');
+
 		// needed for fully logout
-		Server::get(IUserSession::class)->setUser(null);
+		$userSession = Server::get(IUserSession::class);
+		$userSession->setUser(null);
 
 		$this->setupManager->tearDown();
 
-		\OC_User::setUserId($user);
+		self::setUserId($user);
 		$this->postLogin();
-		\OC_Util::setupFS($user);
 		if ($this->userManager->userExists($user)) {
-			\OC::$server->getUserFolder($user);
+			$this->setupManager->setupForUser($this->userManager->get($user));
+			Server::get(IRootFolder::class)->getUserFolder($user);
 		}
 	}
 
diff --git a/tests/lib/User/SessionTest.php b/tests/lib/User/SessionTest.php
index 84d5bc898a057..2845979794e83 100644
--- a/tests/lib/User/SessionTest.php
+++ b/tests/lib/User/SessionTest.php
@@ -102,7 +102,7 @@ protected function setUp(): void {
 			])
 			->getMock();
 
-		\OC_User::setIncognitoMode(false);
+		$this->userSession->setIncognitoMode(false);
 	}
 
 	public static function isLoggedInData(): array {