KeyError When Unassigning Content Rules

Environment: Plone 4.3.15 (Archetypes)

Here is what I get when visiting /mysite/myfolder/@@manage-content-rules

After checking one content rule, and clicking Unassign button, the follow error comes up. Any hint to fix this?

Traceback (innermost last):

  • Module ZPublisher.Publish, line 138, in publish
  • Module ZPublisher.mapply, line 77, in mapply
  • Module ZPublisher.Publish, line 48, in call_object
  • Module, line 53, in __ call __
  • Module, line 60, in unassign_rule

KeyError: '/mysite/myfolder'

For the record: I do not know much about the cause, but adding a try/except clause to bypass the KeyError, that fixes the issue and works for me, since the content rules are no longer needed.