internal server error on large file

I am consistently getting an “internal server error” when attempting to upload a large jpg (33 mb, 600 dpi). There are no errors in the logs even with php debugging enabled. This WP instance is running in a docker container. I own the server, and there are no practical limits on resources (512 GB of RAM, 32 processors, 64 threads). I have tried several different images that are roughly the same size. Each time the image uploads successfully, then says “processing” for a minute or so, followed by the error. It looks like it is encountering a limit, but it shouldn’t be. The PHP execution time limit is 15 minutes. I’m stumped and would appreciate a clue as to where to look.


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