Ran upgrade step: Upgrade MailHost.
Upgrade aborted. Error:
Traceback (most recent call last):
  File "/usr/local/Plone/buildout-cache/eggs/Products.CMFPlone-4.1rc3-py2.6.egg/Products/CMFPlone/MigrationTool.py", line 175, in upgrade
    step['step'].doStep(setup)
  File "/usr/local/Plone/buildout-cache/eggs/Products.GenericSetup-1.6.3-py2.6.egg/Products/GenericSetup/upgrade.py", line 142, in doStep
    self.handler(tool)
  File "/usr/local/Plone/buildout-cache/eggs/plone.app.upgrade-1.1rc3-py2.6.egg/plone/app/upgrade/v40/alphas.py", line 441, in migrateFolders
    transaction.savepoint(optimistic=True)
  File "/usr/local/Plone/buildout-cache/eggs/transaction-1.1.1-py2.6.egg/transaction/_manager.py", line 101, in savepoint
    return self.get().savepoint(optimistic)
  File "/usr/local/Plone/buildout-cache/eggs/transaction-1.1.1-py2.6.egg/transaction/_transaction.py", line 260, in savepoint
    self._saveAndRaiseCommitishError() # reraises!
  File "/usr/local/Plone/buildout-cache/eggs/transaction-1.1.1-py2.6.egg/transaction/_transaction.py", line 257, in savepoint
    savepoint = Savepoint(self, optimistic, *self._resources)
  File "/usr/local/Plone/buildout-cache/eggs/transaction-1.1.1-py2.6.egg/transaction/_transaction.py", line 690, in __init__
    savepoint = savepoint()
  File "/usr/local/Plone/buildout-cache/eggs/ZODB3-3.10.3-py2.6-linux-i686.egg/ZODB/Connection.py", line 1123, in savepoint
    self._commit(None)
  File "/usr/local/Plone/buildout-cache/eggs/ZODB3-3.10.3-py2.6-linux-i686.egg/ZODB/Connection.py", line 623, in _commit
    self._store_objects(ObjectWriter(obj), transaction)
  File "/usr/local/Plone/buildout-cache/eggs/ZODB3-3.10.3-py2.6-linux-i686.egg/ZODB/Connection.py", line 658, in _store_objects
    p = writer.serialize(obj)  # This calls __getstate__ of obj
  File "/usr/local/Plone/buildout-cache/eggs/ZODB3-3.10.3-py2.6-linux-i686.egg/ZODB/serialize.py", line 422, in serialize
    return self._dump(meta, obj.__getstate__())
  File "/usr/local/Plone/buildout-cache/eggs/ZODB3-3.10.3-py2.6-linux-i686.egg/ZODB/serialize.py", line 431, in _dump
    self._p.dump(state)
PicklingError: Can't pickle <class 'p4a.audio.interfaces.IAudioSupport'>: import of module p4a.audio.interfaces failed
End of upgrade path, migration has finished
The upgrade path did NOT reach current version
Migration has failed
Dry run selected, transaction aborted
Version Overview

Plone 4.1rc3
Zope 2.13.7
Python 2.6.6 (r266:84292, May 18 2011, 11:33:24) [GCC 4.4.4 20100726 (Red Hat 4.4.4-13)]