diff --git a/zerver/tests/test_auth_backends.py b/zerver/tests/test_auth_backends.py
index 1a77c6e1b9..ce6354c0d1 100644
--- a/zerver/tests/test_auth_backends.py
+++ b/zerver/tests/test_auth_backends.py
@@ -1474,13 +1474,13 @@ class SAMLAuthBackendTest(SocialAuthBase):
             result = self.client_get('/login/saml/')
             self.assertEqual(result.status_code, 302)
             self.assertEqual('/login/', result.url)
-            m.assert_called_with("/login/saml/ : Bad idp param.")
+            m.assert_called_with("/login/saml/ : Bad idp param: KeyError: 'idp'.")
 
         with mock.patch('zproject.backends.logging.info') as m:
             result = self.client_get('/login/saml/?idp=bad_idp')
             self.assertEqual(result.status_code, 302)
             self.assertEqual('/login/', result.url)
-            m.assert_called_with("/login/saml/ : Bad idp param.")
+            m.assert_called_with("/login/saml/ : Bad idp param: KeyError: 'bad_idp'.")
 
     def test_social_auth_invalid_email(self) -> None:
         """
diff --git a/zproject/backends.py b/zproject/backends.py
index 771a21f980..fec47b1c19 100644
--- a/zproject/backends.py
+++ b/zproject/backends.py
@@ -1392,10 +1392,10 @@ class SAMLAuthBackend(SocialAuthMixin, SAMLAuth):
         try:
             idp_name = self.strategy.request_data()['idp']
             auth = self._create_saml_auth(idp=self.get_idp(idp_name))
-        except KeyError:
+        except KeyError as e:
             # If the above raise KeyError, it means invalid or no idp was specified,
             # we should log that and redirect to the login page.
-            logging.info("/login/saml/ : Bad idp param.")
+            logging.info("/login/saml/ : Bad idp param: KeyError: {}.".format(e))
             return reverse('zerver.views.auth.login_page',
                            kwargs = {'template_name': 'zerver/login.html'})