diff --git a/ironic_lib/disk_utils.py b/ironic_lib/disk_utils.py
index f1cb9ac4..46d68658 100644
--- a/ironic_lib/disk_utils.py
+++ b/ironic_lib/disk_utils.py
@@ -561,9 +561,11 @@ def _get_configdrive(configdrive, node_uuid, tempdir=None):
 
     try:
         data = io.BytesIO(base64.decode_as_bytes(data))
-    except TypeError:
-        error_msg = (_('Config drive for node %s is not base64 encoded '
-                       'or the content is malformed.') % node_uuid)
+    except Exception as exc:
+        error_msg = (_('Config drive for node %(node)s is not base64 encoded '
+                       'or the content is malformed. %(cls)s: %(err)s.')
+                     % {'node': node_uuid, 'err': exc,
+                        'cls': type(exc).__name__})
         if is_url:
             error_msg += _(' Downloaded from "%s".') % configdrive
         raise exception.InstanceDeployFailure(error_msg)
diff --git a/ironic_lib/tests/test_disk_utils.py b/ironic_lib/tests/test_disk_utils.py
index c8fea87b..a35924e8 100644
--- a/ironic_lib/tests/test_disk_utils.py
+++ b/ironic_lib/tests/test_disk_utils.py
@@ -22,7 +22,6 @@ from unittest import mock
 
 from oslo_concurrency import processutils
 from oslo_config import cfg
-from oslo_serialization import base64
 from oslo_utils import imageutils
 import requests
 
@@ -1013,14 +1012,10 @@ class GetConfigdriveTestCase(base.IronicLibTestCase):
                           'http://1.2.3.4/cd', 'fake-node-uuid')
         self.assertFalse(mock_copy.called)
 
-    @mock.patch.object(base64, 'decode_as_bytes', autospec=True)
-    def test_get_configdrive_base64_error(self, mock_b64, mock_requests,
-                                          mock_copy):
-        mock_b64.side_effect = TypeError
+    def test_get_configdrive_base64_error(self, mock_requests, mock_copy):
         self.assertRaises(exception.InstanceDeployFailure,
                           disk_utils._get_configdrive,
                           'malformed', 'fake-node-uuid')
-        mock_b64.assert_called_once_with('malformed')
         self.assertFalse(mock_copy.called)
 
     @mock.patch.object(gzip, 'GzipFile', autospec=True)