diff --git a/inc/python b/inc/python
index 58d75121ac..6df8da20d7 100644
--- a/inc/python
+++ b/inc/python
@@ -45,10 +45,11 @@ function setup_devstack_virtualenv {
         # versions of pip which removed support for legacy editable installs
         # [1]. Some services on this stable branch still hadn't migrated to
         # module-based configuration [2]. This is not an issue since 2025.2.
+        # We also pin setuptools to the last version to support pkg_resources.
         #
         # [1] https://pip.pypa.io/en/stable/news/#v25-3
         # [2] https://review.opendev.org/c/openstack/governance/+/902807
-        pip_install -U 'pip<25.3' setuptools[core]
+        pip_install -U 'pip<25.3' 'setuptools[core]<81.0.0'
     fi
     if [[ ":$PATH:" != *":$DEVSTACK_VENV/bin:"* ]] ; then
         export PATH="$DEVSTACK_VENV/bin:$PATH"
diff --git a/lib/infra b/lib/infra
index f4760c352c..7f262939f8 100644
--- a/lib/infra
+++ b/lib/infra
@@ -31,7 +31,9 @@ function install_infra {
     local PIP_VIRTUAL_ENV="$REQUIREMENTS_DIR/.venv"
     [ ! -d $PIP_VIRTUAL_ENV ] && ${VIRTUALENV_CMD} $PIP_VIRTUAL_ENV
     # We don't care about testing git pbr in the requirements venv.
-    PIP_VIRTUAL_ENV=$PIP_VIRTUAL_ENV pip_install -U pbr setuptools[core]
+    # NOTE(stephenfin) stable-only change to pin setuptools to the last version
+    # to support pkg_resources
+    PIP_VIRTUAL_ENV=$PIP_VIRTUAL_ENV pip_install -U pbr 'setuptools[core]<81.0.0'
     PIP_VIRTUAL_ENV=$PIP_VIRTUAL_ENV pip_install $REQUIREMENTS_DIR
 
     # Unset the PIP_VIRTUAL_ENV so that PBR does not end up trapped