ERROR com.gwava.ews.archiveimpl.EWSFunctions - ERROR: Operation would change object type, which is not permitted.
There seems to be a corruption of folders in Exchange so they generate errors when accessed.
The error comes just after the log shows what folder was accessed. The items in that folder will need to be moved and the original folder deleted.
This article was originally published in the GWAVA knowledgebase as article ID 2349.