diff --git a/SAS/DataManagement/StorageQueryService/cache.py b/SAS/DataManagement/StorageQueryService/cache.py
index 6b3bd6148e1f9e747df58cdc9dcac279414b98ce..e7e8cd38628be909f5794ba788a3f21c1ef06c26 100644
--- a/SAS/DataManagement/StorageQueryService/cache.py
+++ b/SAS/DataManagement/StorageQueryService/cache.py
@@ -307,7 +307,9 @@ class CacheManager:
             if path in self._cache['paths']:
                 result = self._cache['paths'][path]
             else:
-                result = { 'found': False, 'path':path }
+                result = { 'found': False, 'path':path, 'message': 'unknown error' }
+                if not self.disk_usage.path_resolver.pathExists(path):
+                    result['message'] = 'No such path: %s' % path
 
         logger.info('cache.getDiskUsageForPath result: %s' % result)
         return result