diff --git a/networking_generic_switch/generic_switch_mech.py b/networking_generic_switch/generic_switch_mech.py
index 13621c21..72303108 100644
--- a/networking_generic_switch/generic_switch_mech.py
+++ b/networking_generic_switch/generic_switch_mech.py
@@ -394,16 +394,17 @@ def update_port_postcommit(self, context):
                     if (trunk_details and not
                             switch.support_trunk_on_bond_ports):
                         raise ngs_exc.GenericSwitchNotSupported(
-                            "Trunks are not supported by "
-                            "networking-generic-switch %s.",
-                            switch.device_name)
+                            feature="trunks",
+                            switch=switch.device_name,
+                            error="Trunks are not supported on bond ports.")
                     switch.plug_bond_to_network(port_id, segmentation_id,
                                                 **plug_kwargs)
                 else:
                     if trunk_details and not switch.support_trunk_on_ports:
                         raise ngs_exc.GenericSwitchNotSupported(
                             feature="trunks",
-                            switch=switch.device_name)
+                            switch=switch.device_name,
+                            error="Trunks are not supported on ports.")
                     switch.plug_port_to_network(port_id, segmentation_id,
                                                 **plug_kwargs)
                 LOG.info("Successfully plugged port %(port_id)s in segment "
diff --git a/networking_generic_switch/tests/unit/test_generic_switch_mech.py b/networking_generic_switch/tests/unit/test_generic_switch_mech.py
index 2f946b0c..05c616bb 100644
--- a/networking_generic_switch/tests/unit/test_generic_switch_mech.py
+++ b/networking_generic_switch/tests/unit/test_generic_switch_mech.py
@@ -854,7 +854,12 @@ def test_update_port_postcommit_trunk_not_supported(self, m_pc, m_list):
         self.switch_mock.support_trunk_on_bond_ports = False
         self.switch_mock.support_trunk_on_ports = False
 
-        with self.assertRaises(exceptions.GenericSwitchNotSupported):
+        exception_regex = (
+            'Requested feature trunks is not supported by '
+            'networking-generic-switch on the .*. Trunks are not supported on '
+            'ports.')
+        with self.assertRaisesRegex(exceptions.GenericSwitchNotSupported,
+                                    exception_regex):
             driver.update_port_postcommit(mock_context)
         self.switch_mock.plug_port_to_network.assert_not_called()
         m_pc.assert_not_called()
diff --git a/releasenotes/notes/fix-genericswitchnotsupported-exceptions-80fcdcaadb16ca7b.yaml b/releasenotes/notes/fix-genericswitchnotsupported-exceptions-80fcdcaadb16ca7b.yaml
new file mode 100644
index 00000000..90b6d0c2
--- /dev/null
+++ b/releasenotes/notes/fix-genericswitchnotsupported-exceptions-80fcdcaadb16ca7b.yaml
@@ -0,0 +1,7 @@
+---
+fixes:
+  - |
+    Fixes incorrect instantiations of GenericSwitchNotSupported exceptions. See
+    `LP#2147055
+    <https://bugs.launchpad.net/networking-generic-switch/+bug/2147055>`__ for
+    details.
diff --git a/tox.ini b/tox.ini
index 6f7683d5..e3c265a3 100644
--- a/tox.ini
+++ b/tox.ini
@@ -35,6 +35,7 @@ deps =
     bashate~=2.1.0 # Apache-2.0
     pycodestyle>=2.0.0,<3.0.0 # MIT
     doc8~=1.1.0 # Apache-2.0
+    setuptools<81.0.0
 allowlist_externals = bash
                       {toxinidir}/tools/run_bashate.sh
 commands =