diff --git a/CHANGELOG.md b/CHANGELOG.md
index 1c0d6f84ea..e1a2926c7c 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,7 +4,7 @@ See the [releases page](https://github.com/github/codeql-action/releases) for th
 
 ## [UNRELEASED]
 
-No user facing changes.
+- _Upcoming breaking change_: Add a deprecation warning for customers using CodeQL version 2.20.6 and earlier. These versions of CodeQL were discontinued on 25 June 2026 alongside GitHub Enterprise Server 3.16, and will be unsupported by the next minor release of the CodeQL Action. [#3956](https://github.com/github/codeql-action/pull/3956)
 
 ## 4.36.2 - 04 Jun 2026
 
diff --git a/lib/entry-points.js b/lib/entry-points.js
index 006389be49..568ed179e4 100644
--- a/lib/entry-points.js
+++ b/lib/entry-points.js
@@ -147686,7 +147686,7 @@ var semver = __toESM(require_semver2());
 
 // src/api-compatibility.json
 var maximumVersion = "3.22";
-var minimumVersion = "3.16";
+var minimumVersion = "3.17";
 
 // src/json/index.ts
 function parseString(data) {
@@ -153843,9 +153843,9 @@ async function getCombinedTracerConfig(codeql, config) {
 // src/codeql.ts
 var cachedCodeQL = void 0;
 var CODEQL_MINIMUM_VERSION = "2.19.4";
-var CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
-var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
-var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
+var CODEQL_NEXT_MINIMUM_VERSION = "2.20.7";
+var GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.16";
+var GHES_MOST_RECENT_DEPRECATION_DATE = "2026-06-25";
 var EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";
 async function setupCodeQL(toolsInput, apiDetails, tempDir, variant, defaultCliVersion, rawLanguages, useOverlayAwareDefaultCliVersion, features, logger, checkVersion) {
   try {
diff --git a/src/api-compatibility.json b/src/api-compatibility.json
index 435f8f1d6b..7569440194 100644
--- a/src/api-compatibility.json
+++ b/src/api-compatibility.json
@@ -1 +1 @@
-{"maximumVersion": "3.22", "minimumVersion": "3.16"}
+{"maximumVersion": "3.22", "minimumVersion": "3.17"}
diff --git a/src/codeql.ts b/src/codeql.ts
index 5d78337d2e..cb6bef243e 100644
--- a/src/codeql.ts
+++ b/src/codeql.ts
@@ -272,17 +272,17 @@ const CODEQL_MINIMUM_VERSION = "2.19.4";
 /**
  * This version will shortly become the oldest version of CodeQL that the Action will run with.
  */
-const CODEQL_NEXT_MINIMUM_VERSION = "2.19.4";
+const CODEQL_NEXT_MINIMUM_VERSION = "2.20.7";
 
 /**
  * This is the version of GHES that was most recently deprecated.
  */
-const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.15";
+const GHES_VERSION_MOST_RECENTLY_DEPRECATED = "3.16";
 
 /**
  * This is the deprecation date for the version of GHES that was most recently deprecated.
  */
-const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-04-09";
+const GHES_MOST_RECENT_DEPRECATION_DATE = "2026-06-25";
 
 /** The CLI verbosity level to use for extraction in debug mode. */
 const EXTRACTION_DEBUG_MODE_VERBOSITY = "progress++";