As you may know, I recently posted a message about the following issue: http://bugs.python.org/issue1692335 . The issue has been reviewed by Guido van Rossum yesterday and as it seems there are some serious concerns about breaking the pickle protocol functionality and that's why I please the mailing list subscribers for help. Review of the attached patches by someone who has a deep insight into the pickle protocol would be really appreciated. Let me briefly explain the situation: Before version 2.5, it was perfectly possible to pickle and unpickle subclasses of Exception class with custom initializer parameters. In 2.5 it does not work any more and I think the issue is related to new-style class exceptions introduced in Python 2.5. The bug tracker contains patch that fixes the issue and adds some useful test cases. The patch seems to be relatively clean and simple, but still it seems necessary that another experienced developer reviews the patch so the issue can be resolved and closed. The issue prevents some existing projects to move to Python 2.5, please help. Regards, Jaroslav Pachola