Thread:Project:Support desk/"Error creating thumbnail: Error code: 2"/reply (13)

Unfortunately I know very little about Unix permissions, being a Windows person myself. At least in Windows you get a nice user interface to manage permissions! On Linux-based boxes it seems very confusing.

My only suggestion would be to carefully check what user the server or PHP processes are running under, and make sure they have the correct permissions. Or if you try setting the relevant directories' permissions to 777 (temporarily of course), and everything then works, it is evidently a problem of certain users not having the right permissions on the right directories. Keep checking the MediaWiki debug log for information.