diff --git a/extra_data/keydata.py b/extra_data/keydata.py
index 53fd8ab5..f37c58cf 100644
--- a/extra_data/keydata.py
+++ b/extra_data/keydata.py
@@ -1,4 +1,5 @@
 from typing import List, Optional, Tuple
+from warnings import warn
 
 import h5py
 import numpy as np
@@ -301,7 +302,7 @@ def attributes(self):
         if (not attrs) and dset.is_virtual:
             # Virtual datasets were initially created without these attributes.
             # Find a source file. Not using source_file_paths as it can give [].
-            _, filename, _, _ = dset.virtual_sources()[0]
+            filename = dset.id.get_create_plist().get_virtual_filename(0)
             # Not using FileAccess: no need for train or source lists.
             with h5py.File(filename, 'r') as f:
                 attrs = self._find_attributes(f[self.hdf5_data_path])
@@ -610,8 +611,11 @@ def _dim_name(idx):
 
         # xarray attributes
         attrs = {}
-        if (units := self.units):
-            attrs['units'] = units
+        try:
+            if (units := self.units):
+                attrs['units'] = units
+        except Exception as e:
+            warn(f"Exception fetching units: {e}")
 
         if ndarr.dtype.names is not None:
             # Structured dtype.