diff --git a/integrations/opensearch/src/haystack_integrations/document_stores/opensearch/document_store.py b/integrations/opensearch/src/haystack_integrations/document_stores/opensearch/document_store.py
index e9c88274c..f5bbe2b3b 100644
--- a/integrations/opensearch/src/haystack_integrations/document_stores/opensearch/document_store.py
+++ b/integrations/opensearch/src/haystack_integrations/document_stores/opensearch/document_store.py
@@ -181,6 +181,11 @@ def write_documents(self, documents: List[Document], policy: DuplicatePolicy = D
             duplicate_errors_ids = []
             other_errors = []
             for e in errors:
+                # OpenSearch might not return a correctly formatted error, in that case we
+                # treat it as a generic error
+                if "create" not in e:
+                    other_errors.append(e)
+                    continue
                 error_type = e["create"]["error"]["type"]
                 if policy == DuplicatePolicy.FAIL and error_type == "version_conflict_engine_exception":
                     duplicate_errors_ids.append(e["create"]["_id"])
diff --git a/integrations/opensearch/tests/test_document_store.py b/integrations/opensearch/tests/test_document_store.py
index bc0d1c434..8e984953d 100644
--- a/integrations/opensearch/tests/test_document_store.py
+++ b/integrations/opensearch/tests/test_document_store.py
@@ -324,3 +324,12 @@ def test_write_documents_different_embedding_sizes_fail(
 
         with pytest.raises(DocumentStoreError):
             document_store_embedding_dim_4.write_documents(docs)
+
+    @patch("haystack_integrations.document_stores.opensearch.document_store.bulk")
+    def test_write_documents_with_badly_formatted_bulk_errors(self, mock_bulk, document_store):
+        error = {"some_key": "some_value"}
+        mock_bulk.return_value = ([], [error])
+
+        with pytest.raises(DocumentStoreError) as e:
+            document_store.write_documents([Document(content="Hello world")])
+            e.match(f"{error}")