https://www.mediawiki.org/wiki/Manual:$wgMaxShellMemory
On almost all my new MW installations I noticed the problem, that ImageMagick generation of thumbnail view for example in Special:ListFiles fatally fails for GIF images. This is known for insiders (see https://www.mediawiki.org/wiki/Manual:$wgMaxShellMemory If generating thumbnails with ImageMagick fails with a web server error log message like "Memory allocation failed" or "/bin/ulimit4.sh: Segmentation fault /usr/bin/convert ...", the $wgMaxShellMemory value may need to be increased. )
I suggest to increase the standard value to for example to 512000
Version: 1.20.x
Severity: enhancement
URL: https://www.mediawiki.org/wiki/Manual:$wgMaxShellMemory
See Also:
https://bugzilla.wikimedia.org/show_bug.cgi?id=56066