Wikimedia Bugzilla is closed!

If the thumbnail or source image lives in a path containing a space (IE:
C:\Program Files), then when $wgUseImageMagick is set, the thumbnail will fail
to be created, under windows.

To get around this, you merely need to insert quotation marks around the
filenames. These lines are intended to replace lines 462-465 of includes/Image.php:

$cmd  =  $wgImageMagickConvertCommand .
					" -quality 85 -background white -geometry {$width} \"".
					($this->imagePath) . "\" \"" .
					($thumbPath) . "\"";