Okay works now.
(If you're interested, when I went to repost the crop, I accidentally selected the wrong file to attach, and it happened that the file in question was too large. I said Okay to the error, went back and tried to select the crop, but the same error occurred, even though the file I was selecting was small enough. I restarted my session and then was able to upload the crop without any issues. A small bug you could report to your provider if you can be bothered)