The portal checks the file size range, the format and the dimensions before it looks at the photo itself, and it limits how many times you can try. The usual failures are a file over 250 KB straight from a phone camera, a PNG, or a photo where the face is too small or too close to the edge.

This preset exports a 630×810 JPEG, keeps the file between 10 and 250 KB automatically, and shows the result in green when it fits. Then check the face: eyes in the upper third, head filling about three quarters of the height, plain background.

Try it on your own photoDrop a photo at the top of the page. Ten seconds later it's sized, sharpened and ready to post.
Compress a photo