Steps to reproduce the issue:
In 2.8.0, I received 500 errors when uploading a jpeg that had high-resolution (E.g. 4032 × 3024). Thumbnail settings and data (MB) size didn’t seem to matter.
Resolution:
I set the “Reduce Image Width (and Height)” options to 2000. Afterwards images uploaded successfully.
I didn’t troubleshoot this further, but I wanted to report this to hopefully help others. Thanks!