I have 5 MediaWiki installations which has stopped displaying thumbnails in the image gallery index.php?title=Speciel:Newimages. It only affects the thumbnails, the full scale images are working fine. Instead of the thumbnails, it displays the message "Incomplete GD library configuration: missing function imagecreatefrompng".
At first I thought the problem started because I imported image metadata in a XML file and inserted images to the image directories, from another MediaWiki installation, but this should only affect the Wiki importing the image metadata, not all of them I suppose. They do use the same database though.
If it has any significans I am using a Windows 2003 server with IIS 6.0
What can course this problem?
Henrik