Since upgrading to OSX 10.9 I seem to have this issue when running trial (tried it with Twisted 13.0.0, 13.2.0 and 14.0.0): Unexpected error while writing cache file Traceback (most recent call last): File "/usr/local/lib/python2.7/site-packages/twisted/scripts/trial.py", line 472, in postOptions _BasicOptions.postOptions(self) File "/usr/local/lib/python2.7/site-packages/twisted/scripts/trial.py", line 382, in postOptions self['reporter'] = self._loadReporterByName(self['reporter']) File "/usr/local/lib/python2.7/site-packages/twisted/scripts/trial.py", line 369, in _loadReporterByName for p in plugin.getPlugins(itrial.IReporter): File "/usr/local/lib/python2.7/site-packages/twisted/plugin.py", line 209, in getPlugins allDropins = getCache(package) --- <exception caught here> --- File "/usr/local/lib/python2.7/site-packages/twisted/plugin.py", line 181, in getCache dropinPath.setContent(pickle.dumps(dropinDotCache)) The only zip on the path is the pseudo python27.zip. Any ideas? -J