[ZODB-Dev] POSKeyError with Zope 2.7.2, suddenly appeared, then disappeared...

[Tim Peters]

A POSKeyError occurs when a request to load an object is made, but the
database doesn't know about the object being requested.  It's akin to the
KeyError you get if you ask a Python dict for the value associated with key
(say) 'chris' when the dict doesn't have such a key.

POSKeyError "shouldn't" happen.  There are cooperating bugs in Zope 2.7.2 +
ZODB 3.2.3 that can create POSKeyErrors, and presumption has to favor that
you bumped into one of these, especially since your problem appeared to "go
away by magic" later.  Those bugs were fixed in Zope 2.7.3 + ZODB 3.2.4.
Zope 2.7.4 + ZODB 3.2.5 are the current releases.

You should check your FileStorage for problems (fstest & fsrefs):

    http://zope.org/Wikis/ZODB/FileStorageBackup