Upgrading from zope 2.9.3 to zope 2.9.4 running plone 2.5 and various products got... _log() got an unexpected keyword argument 'error' on plone pages. I didn't look hard at the problem (can't get my head around zope) but it seems to be a known problem in zope ... http://www.zope.org/Collectors/Zope/2155 Someone updated the name of a parameter without changing the code that uses it - sigh. This fix doesn't seem to have made it to a release so find enclosed the patch of the edits described in the page above. With this patch it works fine.
Created attachment 95067 [details, diff] patch of described fix
Created attachment 95068 [details, diff] correction of previous patch got a bit confused when generating previous patch - it includes one of the source files - hmm. This one is simple changes to 4 source files.
Fixed, without version bump, please test