diff --git a/rapidannotator/modules/add_experiment/views.py b/rapidannotator/modules/add_experiment/views.py
index 245b7a3..39165dc 100644
--- a/rapidannotator/modules/add_experiment/views.py
+++ b/rapidannotator/modules/add_experiment/views.py
@@ -1038,6 +1038,9 @@ def _editAnnotator():
                         experiment_id=experimentId,
                         user_id=annotatorId).first()
 
+    if annotatorDetails is None:
+        return jsonify({'success': False, 'message': 'Annotator not found for this experiment'}), 404
+
     annotatorDetails.start = request.args.get('start', annotatorDetails.start)
     annotatorDetails.end = request.args.get('end', annotatorDetails.end)
     annotatorDetails.current = 0