diff --git a/deepchem/data/data_loader.py b/deepchem/data/data_loader.py
index 3bcfd8e7e6..35308d4cfb 100644
--- a/deepchem/data/data_loader.py
+++ b/deepchem/data/data_loader.py
@@ -908,7 +908,11 @@ def _featurize_shard(self,
         features = [
             elt for (is_valid, elt) in zip(valid_inds, features) if is_valid
         ]
-        return np.array(features), valid_inds
+        try:
+            return np.array(features), valid_inds
+        except ValueError as e:
+            logger.warning("Exception message: {}".format(e))
+            return np.asarray(features, dtype=object), valid_inds
 
 
 class FASTALoader(DataLoader):