I made an image to post. I uploaded it to catbox, but poal said the link was expired (it isn't, I just made and checked it). So I tried uploading the image directly. It said it was not in an acceptable format, but it's a .jpg. I renamed the image in case the punctuation in the auto-generated name was throwing it off, but got the same error. Then I made a smaller version of the image with the improved name in case it was timing out or something. Still the error.