What are the most obscure error conditions you've encountered while developing Zopeish[1] applications? [1] ZTK, Grok, Bluebream, the old Zope 3.x KGSes all qualify. I'm talking about situations where the error message/traceback are disconnected from the actual cause. For example, forgetting to add a security declaration in ZCML can cause TraversalError (because ForbiddenAttribute is a subclass of AttributeError), which leads the developer off to a wild goose chase looking for why the attribute is missing (was it misspelled? did it come from an old database?) the first few times this kind of error happens. One of the goals we came up with in the Zope Summit in Halle was to identify the most annoying of these kinds of error messages and fix them. I need your help for the identifying part! Marius Gedminas -- http://pov.lt/ -- Zope 3/BlueBream consulting and development