I think I hit Django bug #6681 yesterday. It’s the kind of bug that triggers only if three completely different conditions are met at the same time, where at least one of them depends on timing. In this case:

• The Apache process must be recently started.
• The first request hitting the Apache process must be for a page that requires reST rendering.
• The reST must have a section that triggers the default interpreted role.

For reference, the exception was:

AttributeError: Values instance has no attribute 'default_reference_context'