--- a/src/eric7/Project/Project.py	Tue Mar 28 16:55:19 2023 +0200
+++ b/src/eric7/Project/Project.py	Wed Mar 29 10:45:00 2023 +0200
@@ -3839,6 +3839,9 @@
         @return project relative path or unchanged path, if path doesn't
             belong to the project (string)
         """
+        if path is None:
+            return ""
+
         try:
             return str(pathlib.Path(path).relative_to(self.ppath))
         except ValueError: