Christian Heimes wrote:
The first four bytes of a pyc file contain the magic header. It must match the magic of the current Python version. The next four bytes contain the pyc_mtime. It must match the mtime of the corresponding .py files as returned by fstat().st_mtime. If the magic doesn't match or the mtime header doesn't match the mtime of the .py file, the pyc is ignored.
... so recompile is required to fix. -- http://mail.python.org/mailman/listinfo/python-list
