_pickle.UnpicklingError: could not find MARK

The error _pickle.UnpicklingError: could not find MARK is raised because the offset of the file is not in the beginning. The solution is to call f.seek(0) before loading the pickle.

I got this error at first _pickle.UnpicklingError: could not find MARK, but that was because I was using the class name in the module name. Once I removed it, it worked like a charm!