Possibly all files affected by the commit in bug 47363 return errors for large thumbnails. (Bug 47363 changed $wgMaxImageArea and $wgMaxAnimatedGifArea to 50 MP)
Example files:
https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Mejeri1.gif/576px-Mejeri1.gif
works for me,
https://upload.wikimedia.org/wikipedia/commons/thumb/b/bf/Mejeri1.gif/577px-Mejeri1.gif
and above does not anymore.
https://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/File-Ulysses_S._Grant_from_West_Point_to_Appomattox_partially_restored.png/276px-File-Ulysses_S._Grant_from_West_Point_to_Appomattox_partially_restored.png
OK
https://upload.wikimedia.org/wikipedia/commons/thumb/0/0a/File-Ulysses_S._Grant_from_West_Point_to_Appomattox_partially_restored.png/476px-File-Ulysses_S._Grant_from_West_Point_to_Appomattox_partially_restored.png
Not OK
(Could not find an appropriate tiff file by now)
Version: wmf-deployment
Severity: normal