We have a pretty strange issue on our Moodle installation. We can't upload support file bigger than 50MB for coderunner questions. When we upload a big file and click "save question", we have a blank 500 error page (screenshot below). Nothing in logs on Moodle side, except in apache access log (but no error message, just 500 response code).
Whereas on a regular file upload in a course, we can upload files up to 512MB. Everything looks well configured for PHP limits and reverse proxy limits.
Do you have any idea of what could cause that ?
Thank you !