
I get the following error immediately after I upload an image or a new version of an image:
Error creating thumbnail: convert: Memory allocation failed `Cannot allocate memory' @ exception.c/AcquireExceptionInfo/108.
Here's a screenshot of
File:Pcdsaturn.jpg right after I uploaded a new version of the picture:

Refreshing a page that suddenly links to a thumbnail of the new image apparently causes the error to disappear completely and the thumbnail to be generated normally; CTRL+F5 on the image page also works.
EDIT: Got another malloc after uploading new versions of Gtfares.jpg, Gtferinyes.jpg, Gtfhercules.jpg and Gtfloki.jpg. A different error shows up after I've uploaded the new Gtfloki.jpg and updated the {{shipimage}} on the
GTF Loki article, changing "Image" to "File", adding a resize parameter to the linked file and changing the caption.
Error creating thumbnail: convert: Memory allocation failed `Cannot allocate memory' @ cache.c/AcquirePixelCacheNexus/294.
convert: unable to allocate string `Cannot allocate memory' @ string.c/ConstantString/637.
convert: magick/semaphore.c:344: LockSemaphoreInfo: Assertion `semaphore_info != (SemaphoreInfo *) ((void *)0)' failed.

EDIT2: It looks like the malloc also results in a HTTP 524 error that requires the user to either clear their cache or switch to private browsing mode in order to continue working.