Watch out: Python 2.4 ZEO client and Python 2.6 ZEO Server
Today was interesting when an issue with saving content on a Plone 3.3.5 site got reported to me. The system was producing undecipherable error messages about ZEO disconnections and database conflicts whenever someone would try and create some content within Plone (folders, particularly). Errors looked like:
Module ZEO.zrpc.connection, line 796, in wait. DisconnectedError" and "raise ReadConflictError(). ReadConflictError: database read conflict error"
ERROR ZEO.zrpc (2515) can't decode message: '(K\x11K\x01U\tserialnos(]((U\x08\x00\x00\x00\x00\x00X\x...'
— essentially the issue described here. My ZEO server was running ZODB3 3.9.5 …