Dear Nima,
i have not seen this error so far. I am inclined to believe
that this is due to a local modification or extension of
xowiki.
The error was caused in
Package ad_instproc get_parameter ...
and seems due to the fact that
Package instproc require_folder_object ...
was not executed as it should from
Package instproc init
The "randomness" can be due to the fact that some
connection threads might contain broken objects
which are for some unknown reasons not cleaned
up after some requests.
greetings from key west
-gustaf neumann
