A window can abort while loading because its file is missing, a module is unavailable, a locale symbol is absent or the expected window dictionary was not produced. Fixing the generic wrapper text is not the goal; identify the first underlying exception and the frame that raised it.
A short triage table
AttributeError: inspect the exact module/object and requested attribute. For a locale symbol, compare the spelling and the locale file/module actually loaded.
ImportError: identify whether the dependency is a Python file, a packed module or a native module exported by this client build. A module available inside the game may not exist in an external desktop interpreter.
NameError: find where that name should have been defined or imported, and check the execution branch.
KeyError: inspect the dictionary and expected key. For a UI 'window' key, establish whether the script completed and defined the expected dictionary before the lookup.
Synthetic example, not a patch for your client:
AttributeError: module has no attribute M2CITY_TITLE
Questions:
- Which module object is being used?
- Does its active locale definition contain this exact symbol?
- Was a different locale branch or package loaded?Keep changes narrow
Add or correct a symbol only when you know its intended meaning and where the relevant module loads it. A blanket replacement of the UI loader or a broad exception handler can suppress the traceback while leaving the interface incomplete. Test the window in every locale or feature branch that your change touches.
What counts as verified
The target window opens, the affected control displays the intended text or data, and the corresponding traceback no longer appears. Record both the Python/UI file and any locale data changed.
Reference
A community UI/locale failure illustrates an attribute lookup during script loading. The classification and investigation checklist above are an original explanation, not a universal replacement for ui.py.