# The following code can be used to delete an object that is return POSKeyErrors 
# on a ZODB database. Run it using 'zopectl debug'. Tested with Zope 2.9.
 
container_id = '/path/to/container'
screwed_object_id = 'screwed_obj'
 
from ZODB.POSException import POSKeyError
import transaction
obj = app.unrestrictedTraverse(container_id)
obj._objects = tuple(filter(lambda i,n = id: i['id'] != n, obj._objects))
delattr(obj, screwed_object_id)
transaction.commit()