Plone 3.0 is a lot more tightlipped about displaying potentially sensitive error messages. Instead it just displays a log number which can then be used to send in feedback. That's great. Except when you're writing browsertests, because then you don't have a log to look up the number...

Naturally, this makes debugging page templates using browser tests more tedious (than it already is). Solution? Use the verbose error message template from Plone 2.5. Like so:

svn cat https://svn.plone.org/svn/plone/CMFPlone/tags/2.5.3/skins/plone_templates/default_error_message.pt > parts/plone/CMFPlone/skins/plone_templates/default_error_message.pt

Now you can actually see which attribute caused an AttributeError etc. Usually, that helps ;-)