diff --git a/global-requirements.txt b/global-requirements.txt
index a0913e3c8..bc1e8f5fb 100644
--- a/global-requirements.txt
+++ b/global-requirements.txt
@@ -72,6 +72,7 @@ grpcio  # Apache-2.0
 gunicorn  # MIT
 httplib2  # MIT
 httpx  # BSD
+Hypercorn  # MIT
 hvac  # Apache-2.0
 icalendar  # BSD
 # Do not make importlib-metadata conditional on Python version: we depend on
diff --git a/openstack_requirements/check.py b/openstack_requirements/check.py
index 7b6711b24..69e417e5e 100644
--- a/openstack_requirements/check.py
+++ b/openstack_requirements/check.py
@@ -129,7 +129,6 @@ def _is_requirement_in_global_reqs(
     local_req,
     global_reqs,
     backports,
-    allow_3_only=False,
 ):
     req_exclusions = _get_exclusions(local_req)
     for global_req in global_reqs:
@@ -138,10 +137,10 @@ def _is_requirement_in_global_reqs(
             local_req_val = getattr(local_req, aname)
             global_req_val = getattr(global_req, aname)
             if local_req_val != global_req_val:
-                # if a python 3 version is not spefied in only one of
+                # if a python 3 version is not specified in only one of
                 # global requirements or local requirements, allow it since
                 # python 3-only is okay
-                if allow_3_only and matching and aname == 'markers':
+                if matching and aname == 'markers':
                     if not local_req_val and PY3_GLOBAL_SPECIFIER_RE.match(
                         global_req_val
                     ):
@@ -250,7 +249,6 @@ def _validate_one(
     denylist,
     global_reqs,
     backports,
-    allow_3_only=False,
 ):
     """Returns True if there is a failure."""
 
@@ -276,7 +274,6 @@ def _validate_one(
             req,
             global_reqs[name],
             backports,
-            allow_3_only,
         ):
             return True
 
@@ -289,22 +286,8 @@ def _validate_one(
             return True
 
     for extra, count in counts.items():
-        # Make sure the number of entries matches. If allow_3_only, then we
-        # just need to make sure we have at least the number of entries for
-        # supported Python 3 versions.
+        # Make sure the number of entries matches.
         if count != len(global_reqs[name]):
-            if allow_3_only and count >= len(
-                _get_python3_reqs(global_reqs[name])
-            ):
-                print(
-                    "WARNING (probably OK for Ussuri and later): "
-                    "Package '{}{}' is only tracking python 3 "
-                    "requirements".format(
-                        name, (f'[{extra}]') if extra else ''
-                    )
-                )
-                continue
-
             print(
                 "ERROR: Package '{}{}' requirement does not match "
                 "number of lines ({}) in "
@@ -324,7 +307,6 @@ def validate(
     denylist,
     global_reqs,
     backports,
-    allow_3_only=False,
 ):
     failed = False
     # iterate through the changing entries and see if they match the global
@@ -339,7 +321,6 @@ def validate(
                     denylist,
                     global_reqs,
                     backports,
-                    allow_3_only,
                 )
                 or failed
             )
diff --git a/openstack_requirements/project.py b/openstack_requirements/project.py
index a83035f9f..4f8eafcd2 100644
--- a/openstack_requirements/project.py
+++ b/openstack_requirements/project.py
@@ -123,6 +123,35 @@ def _read_setup_cfg_extras(root: str) -> dict[str, list[str]] | None:
     return result
 
 
+def verify_pyproject_toml(root: str) -> bool:
+    data = _read_pyproject_toml(root)
+
+    if data is None:
+        print('Missing pyproject.toml file', file=sys.stderr)
+        return False
+
+    if 'build-system' not in data:
+        print("pyproject.toml is missing 'build-system' table", file=sys.stderr)
+        return False
+
+    if (build_backend := data['build-system'].get('build-backend')) != 'pbr.build':
+        print(
+            f"pyproject.toml has invalid 'build-system.build-backend'. "
+            f"Expected 'pbr.build'; got {build_backend!r}",
+            file=sys.stderr,
+        )
+        return False
+
+    if 'project' not in data:
+        print(
+            "pyproject.toml is missing 'project' table. This is not currently "
+            "an error but may be in the future",
+            file=sys.stderr,
+        )
+
+    return True
+
+
 class Project(TypedDict):
     # The root directory path
     root: str
diff --git a/openstack_requirements/tests/test_check.py b/openstack_requirements/tests/test_check.py
index d74b4925e..65b5d8848 100644
--- a/openstack_requirements/tests/test_check.py
+++ b/openstack_requirements/tests/test_check.py
@@ -113,7 +113,6 @@ def test_match_with_local_markers(self):
                 req,
                 self.global_reqs['name'],
                 self.backports,
-                allow_3_only=True,
             )
         )
 
@@ -133,7 +132,6 @@ def test_match_without_python3_markers(self):
                 req,
                 self.global_reqs['withmarker'],
                 self.backports,
-                allow_3_only=True,
             )
         )
 
@@ -451,110 +449,6 @@ def test_new_item_mismatches_global_list_with_extra(self):
             )
         )
 
-    def test_new_item_matches_py3_allowed_no_version(self):
-        # If the global list has multiple entries for an item but the branch
-        # allows python 3 only, then only the py3 entries need to match.
-        # Requirements without a python_version marker should always be used.
-        r_content = textwrap.dedent("""
-        name>=1.5;python_version=='3.5'
-        other-name
-        """)
-        reqs = [r for r, line in requirement.parse(r_content)['name']]
-        global_reqs = check.get_global_reqs(
-            textwrap.dedent("""
-        name>=1.5;python_version=='3.5'
-        name>=1.2,!=1.4;python_version=='2.6'
-        other-name
-        """)
-        )
-        self.assertFalse(
-            check._validate_one(
-                'name',
-                reqs=reqs,
-                denylist=requirement.parse(''),
-                backports=self.backports,
-                global_reqs=global_reqs,
-                allow_3_only=True,
-            )
-        )
-
-    def test_new_item_matches_py3_allowed(self):
-        # If the global list has multiple entries for an item but the branch
-        # allows python 3 only, then only the py3 entries need to match.
-        # Requirements without a python_version marker should always be used.
-        r_content = textwrap.dedent("""
-        name>=1.5
-        other-name
-        """)
-        reqs = [r for r, line in requirement.parse(r_content)['name']]
-        global_reqs = check.get_global_reqs(
-            textwrap.dedent("""
-        name>=1.5;python_version>='3.5'
-        name>=1.2,!=1.4;python_version=='2.6'
-        other-name
-        """)
-        )
-        self.assertFalse(
-            check._validate_one(
-                'name',
-                reqs=reqs,
-                denylist=requirement.parse(''),
-                backports=self.backports,
-                global_reqs=global_reqs,
-                allow_3_only=True,
-            )
-        )
-
-    def test_new_item_matches_py3_allowed_with_py2(self):
-        # If the global list has multiple entries for an item but the branch
-        # allows python 3 only, then only the py3 entries need to match.
-        # It should continue to pass with py2 entries though.
-        r_content = textwrap.dedent("""
-        name>=1.5;python_version=='3.5'
-        name>=1.2,!=1.4;python_version=='2.6'
-        """)
-        reqs = [r for r, line in requirement.parse(r_content)['name']]
-        global_reqs = check.get_global_reqs(
-            textwrap.dedent("""
-        name>=1.5;python_version=='3.5'
-        name>=1.2,!=1.4;python_version=='2.6'
-        """)
-        )
-        self.assertFalse(
-            check._validate_one(
-                'name',
-                reqs=reqs,
-                denylist=requirement.parse(''),
-                backports=self.backports,
-                global_reqs=global_reqs,
-                allow_3_only=True,
-            )
-        )
-
-    def test_new_item_matches_py3_allowed_no_py2(self):
-        # If the global list has multiple entries for an item but the branch
-        # allows python 3 only, then only the py3 entries need to match.
-        r_content = textwrap.dedent("""
-        name>=1.5;python_version=='3.5'
-        """)
-        reqs = [r for r, line in requirement.parse(r_content)['name']]
-        global_reqs = check.get_global_reqs(
-            textwrap.dedent("""
-        name>=1.5;python_version=='3.5'
-        name>=1.2,!=1.4;python_version=='2.6'
-        """)
-        )
-        self.assertFalse(
-            check._validate_one(
-                'name',
-                reqs=reqs,
-                denylist=requirement.parse(''),
-                backports=self.backports,
-                global_reqs=global_reqs,
-                allow_3_only=True,
-            )
-        )
-
 
 class TestBackportPythonMarkers(testtools.TestCase):
     def setUp(self):
@@ -581,7 +475,6 @@ def test_notmatching_no_backport(self):
                 self.req,
                 self.global_reqs["name"],
                 list(backports.keys()),
-                allow_3_only=True,
             )
         )
 
@@ -595,6 +488,5 @@ def test_notmatching_with_backport(self):
                 self.req,
                 self.global_reqs["name"],
                 list(backports.keys()),
-                allow_3_only=True,
             )
         )
diff --git a/openstack_requirements/tests/test_project.py b/openstack_requirements/tests/test_project.py
index a90146d66..e2139c236 100644
--- a/openstack_requirements/tests/test_project.py
+++ b/openstack_requirements/tests/test_project.py
@@ -10,6 +10,7 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
+from io import StringIO
 import os
 import textwrap
 
@@ -56,6 +57,73 @@ def test_empty(self):
         )
 
 
+class TestVerifyPyprojectToml(testtools.TestCase):
+    def setUp(self):
+        super().setUp()
+        self.stderr = StringIO()
+        self.useFixture(fixtures.MonkeyPatch('sys.stderr', self.stderr))
+
+    def test_valid(self):
+        root = self.useFixture(common.pep_518_fixture).root
+        self.assertTrue(project.verify_pyproject_toml(root))
+        self.assertEqual('', self.stderr.getvalue())
+
+    def test_missing_file(self):
+        root = self.useFixture(fixtures.TempDir()).path
+        self.assertFalse(project.verify_pyproject_toml(root))
+        self.assertEqual(
+            'Missing pyproject.toml file\n', self.stderr.getvalue()
+        )
+
+    def test_missing_build_system(self):
+        root = self.useFixture(fixtures.TempDir()).path
+        with open(os.path.join(root, 'pyproject.toml'), 'w') as fh:
+            fh.write(
+                textwrap.dedent("""
+                [project]
+                name = "foo"
+                """)
+            )
+        self.assertFalse(project.verify_pyproject_toml(root))
+        self.assertIn(
+            "pyproject.toml is missing 'build-system' table",
+            self.stderr.getvalue(),
+        )
+
+    def test_invalid_build_backend(self):
+        root = self.useFixture(fixtures.TempDir()).path
+        with open(os.path.join(root, 'pyproject.toml'), 'w') as fh:
+            fh.write(
+                textwrap.dedent("""
+                [build-system]
+                requires = ["setuptools"]
+                build-backend = "setuptools.build_meta"
+                """)
+            )
+        self.assertFalse(project.verify_pyproject_toml(root))
+        self.assertIn(
+            "pyproject.toml has invalid 'build-system.build-backend'. "
+            "Expected 'pbr.build'; got 'setuptools.build_meta'",
+            self.stderr.getvalue(),
+        )
+
+    def test_missing_project_table(self):
+        root = self.useFixture(fixtures.TempDir()).path
+        with open(os.path.join(root, 'pyproject.toml'), 'w') as fh:
+            fh.write(
+                textwrap.dedent("""
+                [build-system]
+                requires = ["pbr>=6.0.0", "setuptools>=64.0.0"]
+                build-backend = "pbr.build"
+                """)
+            )
+        self.assertTrue(project.verify_pyproject_toml(root))
+        self.assertIn(
+            "pyproject.toml is missing 'project' table",
+            self.stderr.getvalue(),
+        )
+
+
 class TestProjectExtras(testtools.TestCase):
     def test_pyproject_toml(self):
         root = self.useFixture(fixtures.TempDir()).path
diff --git a/playbooks/files/project-requirements-change.py b/playbooks/files/project-requirements-change.py
index 1a997e486..1baf73733 100755
--- a/playbooks/files/project-requirements-change.py
+++ b/playbooks/files/project-requirements-change.py
@@ -18,7 +18,6 @@
 import argparse
 import contextlib
 import os
-import re
 import shlex
 import shutil
 import subprocess
@@ -30,9 +29,6 @@
 from openstack_requirements import requirement  # noqa
 
 
-PYTHON_3_BRANCH = re.compile(r'^stable\/[u-z].*')
-
-
 def run_command(cmd):
     print(cmd)
     cmd_list = shlex.split(str(cmd))
@@ -130,6 +126,14 @@ def main():
             backports = {}
 
         cwd = os.getcwd()
+
+        # Verify that pyproject.toml is present and contains the required
+        # attributes. We only do this on master since we don't want to be
+        # strict on already released branches
+        pyproject_found = None
+        if branch in ('master', 'main'):
+            pyproject_found = project.verify_pyproject_toml(cwd)
+
         # build a list of requirements in the proposed change,
         # and check them for style violations while doing so
         head_proj = project.read(cwd)
@@ -144,21 +148,23 @@ def main():
         #    either.
         head_strict = not branch.startswith('stable/')
         head_reqs.process(strict=head_strict)
-        # Starting with Ussuri and later, we only need to be strict about
-        # Python 3 requirements.
-        python_3_branch = head_strict or PYTHON_3_BRANCH.match(branch)
 
         failed = check.validate(
             head_reqs,
             denylist,
             global_reqs,
             list(backports.keys()),
-            allow_3_only=python_3_branch,
         )
 
     # report the results
+    error = False
     if failed or head_reqs.failed:
         print("*** Incompatible requirement found!")
+        error = True
+    if pyproject_found is False:
+        print("*** Invalid or missing pyproject.toml!")
+        error = True
+    if error:
         print("*** See https://docs.openstack.org/requirements/latest/")
         sys.exit(1)
 
diff --git a/upper-constraints.txt b/upper-constraints.txt
index 3ad73d84c..9b4cdcadd 100644
--- a/upper-constraints.txt
+++ b/upper-constraints.txt
@@ -58,18 +58,19 @@ python-mistralclient===6.2.0
 oslo.context===6.4.0
 rcssmin===1.2.2
 pycadf===4.0.1
-grpcio===1.81.0
+grpcio===1.81.1
 sniffio===1.3.1
 fixtures===4.3.2
-neutron-lib===4.0.0
+neutron-lib===4.1.0
 XStatic-FileSaver===1.3.2.1
 jaraco.functools===4.5.0
 oslo.metrics===0.16.0
 storage-interfaces===1.0.5
 pydantic===2.13.4
+Hypercorn===0.18.0
 pystache===0.6.8
 XStatic-Font-Awesome===6.2.1.2
-aiohttp===3.14.0
+aiohttp===3.14.1
 waitress===3.0.2
 os-refresh-config===14.0.1
 pysnmp===7.1.27
@@ -80,11 +81,11 @@ sphinx-copybutton===0.5.2
 beartype===0.22.9
 ddt===1.7.2
 pyserial===3.5
-moto===5.2.1
+moto===5.2.2
 infi.dtypes.wwn===0.1.1
 awscrt===0.34.1
 pcre2===0.6.0
-python-freezerclient===6.3.0
+python-freezerclient===6.4.0
 python-vitrageclient===5.4.0
 py-pure-client===1.88.0
 krest===1.3.8
@@ -129,11 +130,11 @@ jsonpointer===3.1.1
 defusedxml===0.7.1
 opentelemetry-sdk===1.42.1
 netaddr===1.3.0
-pyghmi===1.6.16
+pyghmi===1.6.17
 sphinxcontrib-blockdiag===3.0.0
 aiosqlite===0.22.1
 gnocchiclient===7.2.0
-wcwidth===0.8.0
+wcwidth===0.8.1
 sphinxcontrib.datatemplates===0.11.0
 jsonpath-rw===1.4.0
 prettytable===3.17.0
@@ -147,7 +148,7 @@ async-timeout===5.0.1
 virtualbmc===3.3.0
 SQLAlchemy===2.0.50
 pyroute2===0.8.1
-google-auth===2.53.0
+google-auth===2.54.0
 kazoo===2.11.0
 pyspnego===0.12.1
 trio-websocket===0.12.2
@@ -177,7 +178,7 @@ python-subunit===1.4.6
 pycparser===3.0
 mock===5.2.0
 PyYAML===6.0.3
-beautifulsoup4===4.14.3
+beautifulsoup4===4.15.0
 ovs===3.7.1
 cryptography===43.0.3
 httpcore===1.0.9
@@ -197,7 +198,7 @@ tzlocal===5.3.1
 sysv_ipc===1.2.0
 sphinxcontrib-jsmath===1.0.1
 django_compressor===4.6.0
-awscurl===0.42
+awscurl===0.44
 trio===0.33.0
 python-novaclient===18.13.0
 pact===1.12.0
@@ -286,7 +287,7 @@ pydantic_core===2.46.4
 uritemplate===4.2.0
 docutils===0.21.2
 threadpoolctl===3.6.0
-os-ken===4.2.0
+os-ken===4.2.1
 ujson===5.12.1
 selenium===4.44.0
 pytest-subtests===0.15.0
@@ -300,7 +301,7 @@ capacity===1.3.14
 playwright===1.60.0
 markdown-it-py===4.2.0
 retrying===1.4.2
-python-discovery===1.4.0
+python-discovery===1.4.2
 platformdirs===4.10.0
 pydotplus===2.0.2
 boto3===1.35.99
@@ -354,7 +355,7 @@ keystonemiddleware===13.0.0
 django-formtools===2.6.1
 XStatic-Spin===1.2.5.3
 rich===15.0.0
-os-traits===3.6.0
+os-traits===3.8.0
 typepy===1.3.5
 SecretStorage===3.5.0
 XStatic-Rickshaw===1.5.1.3
@@ -385,9 +386,9 @@ python-consul===1.1.0
 more-itertools===11.1.0
 seqdiag===3.0.0
 numpy===2.4.6
-msgpack===1.1.2
+msgpack===1.2.0
 Sphinx===9.0.4
-oslo.config===10.4.0
+oslo.config===10.5.0
 openstackdocstheme===3.6.0
 osc-placement===4.8.0
 rpds-py===2026.5.1
@@ -405,7 +406,7 @@ pytest-metadata===3.1.1
 pyparsing===3.3.2
 geomet===1.1.0
 opentelemetry-exporter-otlp-proto-common===1.42.1
-distlib===0.4.1
+distlib===0.4.3
 ast_serialize===0.5.0
 dogpile.cache===1.5.0
 python-barbicanclient===7.4.0
@@ -438,7 +439,7 @@ cotyledon===2.2.0
 xattr===1.3.0
 systemd-python===235
 python-memcached===1.62
-openstacksdk===4.14.0
+openstacksdk===4.16.0
 infi.dtypes.nqn===0.1.0
 six===1.17.0
 h2===4.3.0
@@ -453,14 +454,14 @@ requestsexceptions===1.4.0
 testresources===2.1.2
 falcon===4.2.0
 tomlkit===0.15.0
-etcd3gw===2.6.0
+etcd3gw===2.7.0
 Flask-RESTful===0.3.10
 GitPython===3.1.50
 python-ironicclient===6.1.0
 babel===2.18.0
 XStatic===1.0.3
 XStatic-Angular-FileUpload===12.2.13.2
-python-openstackclient===10.0.0
+python-openstackclient===10.1.0
 pyzmq===27.1.0
 oslo.db===18.0.0
 simplegeneric===0.8.1
@@ -556,16 +557,16 @@ importlib_metadata===9.0.0
 sortedcontainers===2.4.0
 microversion_parse===2.1.0
 python-linstor===1.28.1
-filelock===3.29.1
+filelock===3.29.3
 python-tackerclient===2.5.0
 python-heatclient===5.2.0
-oslo.utils===10.1.0
+oslo.utils===10.1.1
 requests-kerberos===0.15.0
 itsdangerous===2.2.0
 XStatic-jquery-ui===1.13.0.2
 monasca-statsd===2.7.0
 python-dateutil===2.9.0.post0
-virtualenv===21.4.2
+virtualenv===21.4.3
 colorama===0.4.6
 confetti===2.5.3
 ironic-lib===7.0.0