I traced it down to this method, where fileName = 'C:\Squeak 4.1\package-cache\LayeredProtocol -rww.2.mcz' and writeMode = true.

StandardFileStream>>#open: fileName forWrite: writeMode "Open the file with the given name. If writeMode is true, allow writing, otherwise open the file in read-only mode." "Changed to do a GC and retry before failing ar 3/21/98 17:25" | f | f := fileName asVmPathName. fileID := StandardFileStream retryWithGC:[self primOpen: f writable: writeMode] until:[:id| id notNil] forFileNamed: fileName. fileID ifNil: [^ nil]. "allows sender to detect failure"

The call to #primOpen:writable: is failing silently and returning nil. I have no file by this name on my file system.

This is preventing me from publishing anything. Here is the strange thing...I can publish my other project.

Thanks, Rob