I know, I cross post... Please adjust the destinations as appropriate when you reply. In Zope 2.5.x, "Products.PageTemplates.TALES.Context.evaluate" converts most exceptions into "TALESError" exceptions. This is probably not a good idea for many exceptions. For "ConflictError" (and its subclass "ReadConflictError") it is definitely a bug. It prevents the usual automatic retry of the request and exposes an exception not understandable to a normal user. I think Shane has cleaned up the exception conversion for Zope 2.6. Therefore, I do not file a bug report to the collector. Dieter