diff --git a/mongo_connector/doc_managers/doc_manager_base.py b/mongo_connector/doc_managers/doc_manager_base.py
index 2320b8f9..0fc74b87 100644
--- a/mongo_connector/doc_managers/doc_manager_base.py
+++ b/mongo_connector/doc_managers/doc_manager_base.py
@@ -84,9 +84,11 @@ def _unset_field(doc, to_unset):
                         where[index_or_key] = None
                     else:
                         # Unset field removes it entirely.
-                        del where[index_or_key]
+                        if where and where.get(index_or_key):
+                            del where[index_or_key]
                 else:
-                    del doc[to_unset]
+                    if doc and doc.get(to_unset):
+                        del doc[to_unset]
             except (KeyError, IndexError, ValueError):
                 source_version = get_mininum_mongodb_version()
                 if source_version is None or source_version.at_least(2, 6):