Comment 9 for bug 315247

I have the same problem. The error about the unicode strings is thrown in the isDirectoryInCache(self, path) method of the ImageCache class.

entertainerlib/backend/components/mediacache/image_cache.py

I have added a print statement at the beginning of the function, printing the content of the path variable. The function is called without problems until the file name is "Königreich der Himmel" which contains the german umlaut ö. Python prints the filename as "Königreich der Himmel". So the problem seems to be due to non-ascii characters in the path.