"File could not be found"

New project. When I save a target, I have to wait some 20 seconds and then this message is shown (Swedish): Det går inte att hitta filen (The file could not be found). I have no idea what file. Removing all TMs is no help. Neither is clicking on Knowledge base or Community in the error message (nothing relevant in either place).

I've tried other projects as well (that I have been working on previously without problems): same result.

Need help urgently.

Mats