diff --git a/src/gui_qt/fit/fitwindow.py b/src/gui_qt/fit/fitwindow.py
index 9888685..9bb4db9 100644
--- a/src/gui_qt/fit/fitwindow.py
+++ b/src/gui_qt/fit/fitwindow.py
@@ -286,7 +286,10 @@ class QFitDialog(QtWidgets.QWidget, Ui_FitDialog):
             if model_name in data:
                 parameter, _ = self._prepare(model_parameter, function_use=data[model_name], add_idx=isinstance(func, MultiModel))
 
-                if parameter is None:
+                if parameter is None or not isinstance(parameter, dict):
+                    return
+
+                if ('data_parameter' not in parameter) or ('global_parameter' not in parameter):
                     return
 
                 for (data_parameter, _) in parameter['data_parameter'].values():