diff --git a/keystoneauth1/plugin.py b/keystoneauth1/plugin.py
index 74970af5..f27a9e1a 100644
--- a/keystoneauth1/plugin.py
+++ b/keystoneauth1/plugin.py
@@ -149,7 +149,9 @@ class BaseAuthPlugin(object):
         endpoint_data = self.get_endpoint_data(
             session, endpoint_override=endpoint_override,
             discover_versions=False, **kwargs)
-        return endpoint_data.api_version
+        if endpoint_data:
+            return endpoint_data.api_version
+        return None
 
     def get_endpoint(self, session, **kwargs):
         """Return an endpoint for the client.
diff --git a/keystoneauth1/tests/unit/test_discovery.py b/keystoneauth1/tests/unit/test_discovery.py
index b0cdd9c0..241afe55 100644
--- a/keystoneauth1/tests/unit/test_discovery.py
+++ b/keystoneauth1/tests/unit/test_discovery.py
@@ -560,6 +560,29 @@ class VersionDataTests(utils.TestCase):
 
         self.assertTrue(mock.called_once)
 
+    def test_version_data_legacy_ironic_no_override(self):
+        """Validate detection of legacy Ironic microversion ranges."""
+        ironic_url = 'https://bare-metal.example.com/v1/'
+        self.requests_mock.get(
+            ironic_url, status_code=200,
+            json={
+                'id': 'v1',
+                'links': [{
+                    "href": ironic_url,
+                    "rel": "self"}]},
+            headers={
+                'X-OpenStack-Ironic-API-Minimum-Version': '1.3',
+                'X-OpenStack-Ironic-API-Maximum-Version': '1.21',
+            })
+
+        plugin = noauth.NoAuth()
+        a = adapter.Adapter(
+            self.session,
+            auth=plugin,
+            service_type='baremetal')
+
+        self.assertIsNone(a.get_api_major_version())
+
     def test_version_data_ironic_microversions(self):
         """Validate detection of Ironic microversion ranges."""
         ironic_url = 'https://bare-metal.example.com/v1/'