Unknown mod failure

My mod was working fine until recently. Now when I try to load it the screen goes black and I get an error message that says that M2TW has to close because of an unspecified error (I found out what the error message was by hitting the printscreen key and pasting the image into paint). The error log only says that M2TW had to close because of an unspecified error.

What could be causing this problem and how do I fix it? The .cfg file contains '[io] file_first = 1', and the .bat file contains '--io.file_first'.

The only thing I can tell you is to retrace your steps. Undo the changes and re-apply them one by one to see what's afoot.

Moved to modding questions

I've managed to solve this problem. For some reason moving the battle_models.modeldb file into my vanilla data folder caused this problem. After I put it back into my mod folder my mod worked fine (all the new units were there). However the game used to work when I had the battle_models.modeldb in my vanilla data folder.

Has anyone else had this problem?