Prevent system error when uploading a profile photo that's too large.

Fix

We now show a more useful error message when a user uploads a profile photo that is too large, and take them back to the form where they can choose another photo.

Note: profile photos use our old file uploader and have a 1MB file size limit. This will be updated to use our new photo uploader that allows users to choose from Facebook, Instagram etc and allows much larger images to be uploaded. There isn't a scheduled date for that update yet.