When you are plagued by "ReadConflictError"s, you might be interested in the "ReadCommitted" transaction isolation level. Usually, a transaction receives a "ReadConflictError" when it tries to load an object from ZODB that has been modified since transaction start. Usually, the application will abort the transaction in this case and restart it. When transactions are long or writes a frequent, "ReadConflictError"s can become a plague. That's when the "ReadCommitted" transaction isolation level can step in. Rather than raising a "ReadConflictError", it reads the state as it was when the transaction started, provided the storage supports "undo". If this is not the case, a "ReadConflictError" is raised. You find a patch (against Zope 2.6.1) that provides the "ReadCommitted" isolation level at <http://www.dieter.handshake.de/pyprojects/zope> Dieter