[Setup] Migration error - how to analyze?

[J. Michael Adams]

I've just upgraded my Plone site files from 2.0.5 to 2.1.2, but I get an
error when I try to migrate.

I don't know where to start looking to fix the problem. I see that it's in
the ExternalStorage product, but I don't know where to look in my
application. It must be in some code that I didn't write -- someone else
before me on the project wrote it. 

I've included the error messages below. I'm fairly new to both Zope and
Python, so I could use some help deciphering the messages.

Could anyone give me a hint about where to start looking for the problem? 

Thank you

    *   Dry run selected.
    * Starting the migration from version: 2.0.5
    * Attempting to upgrade from: 2.0.5
    * Upgrade aborted
    * Error type: Products.ATContentTypes.migration.walker.MigrationError
    * Error value: MigrationError for obj at /clients/all/Recordings (CMF
Folder -> Folder): Traceback (most recent call last): File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/walker.py",
line 174, in migrate migrator.migrate() File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/migrator.py",
line 196, in migrate method() File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/migrator.py",
line 517, in migrate_children self.new._setObject(id, obj, set_owner=0) File
"/home/wink/zope/278/lib/python/OFS/ObjectManager.py", line 276, in
_setObject object.manage_afterAdd(object, self) File
"/home/wink/zope/instance1/Products/Archetypes/BaseContent.py", line 37, in
manage_afterAdd BaseObject.manage_afterAdd(self, item, container) File
"/home/wink/zope/instance1/Products/Archetypes/BaseObject.py", line 180, in
manage_afterAdd self.initializeLayers(item, container) File
"/home/wink/zope/instance1/Products/Archetypes/BaseObject.py", line 195, in
initializeLayers self.Schema().initializeLayers(self, item, container) File
"/home/wink/zope/instance1/Products/Archetypes/Schema/__init__.py", line
305, in initializeLayers obj.initializeInstance(instance, item, container)
File
"/home/wink/zope/instance1/Products/ExternalStorage/ExternalStorage.py",
line 77, in initializeInstance self.migrate(instance) File
"/home/wink/zope/instance1/Products/ExternalStorage/ExternalStorage.py",
line 423, in migrate instance._es.update({name: item}) AttributeError: _es
    * File "/home/wink/zope/instance1/Products/CMFPlone/MigrationTool.py",
line 274, in upgrade newv, msgs = self._upgrade(newv)
    * File "/home/wink/zope/instance1/Products/CMFPlone/MigrationTool.py",
line 371, in _upgrade res = function(self.aq_parent)
    * File
"/home/wink/zope/instance1/Products/CMFPlone/migrations/v2_1/alphas.py",
line 69, in two05_alpha1 migrateToATCT10(portal, out)
    * File
"/home/wink/zope/instance1/Products/CMFPlone/migrations/v2_1/alphas.py",
line 298, in migrateToATCT10 tool.migrateToATCT()
    * File
"/home/wink/zope/instance1/Products/ATContentTypes/tool/migration.py", line
240, in migrateToATCT out, elapse, c_elapse =
self.migrateContentTypesToATCT(portal_types=None)
    * File
"/home/wink/zope/instance1/Products/ATContentTypes/tool/migration.py", line
260, in migrateContentTypesToATCT out = migrateAll(portal)
    * File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/atctmigrator.py
", line 239, in migrateAll migrator=migrator, **kwargs)
    * File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/common.py",
line 224, in migratePortalType walk.go()
    * File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/walker.py",
line 126, in go self.migrate(self.walk(), **kwargs)
    * File
"/home/wink/zope/instance1/Products/ATContentTypes/migration/walker.py",
line 205, in migrate raise MigrationError(objpath, migrator, tb)
    * End of upgrade path, migration has finished
    * The upgrade path did NOT reach current version
    * Migration has failed
    * Dry run selected, transaction aborted