diff --git a/src/petab_gui/controllers/mother_controller.py b/src/petab_gui/controllers/mother_controller.py
index 6ad0def..5a72af0 100644
--- a/src/petab_gui/controllers/mother_controller.py
+++ b/src/petab_gui/controllers/mother_controller.py
@@ -10,6 +10,7 @@
 import petab.v1 as petab
 import qtawesome as qta
 import yaml
+from petab.versions import get_major_version
 from PySide6.QtCore import QSettings, Qt, QTimer, QUrl
 from PySide6.QtGui import (
     QAction,
@@ -730,6 +731,12 @@ def open_yaml_and_load_files(self, yaml_path=None, mode="overwrite"):
             with open(yaml_path) as file:
                 yaml_content = yaml.safe_load(file)
 
+            if (major := get_major_version(yaml_content)) != 1:
+                raise ValueError(
+                    f"Only PEtab v1 problems are currently supported. "
+                    f"Detected version: {major}.x."
+                )
+
             # Resolve the directory of the YAML file to handle relative paths
             yaml_dir = Path(yaml_path).parent