To demonstrate the issue, this is my avatar
https://xenforo.com/community/data/avatars/m/1/1110.jpg
Open the image in your browser (I'm using Chrome, windows).
1. Drag the image to your desktop -> you'll get a png image rather than a jpg. If you'll right-click to <Save image as..> it will save as jpg.
2. Right-click to <Save image as..> to get the jpg image. Try to upload it as an attachment to your post, you'll get an error "The contents of the uploaded image do not match the file's extension."
https://xenforo.com/community/data/avatars/m/1/1110.jpg
Open the image in your browser (I'm using Chrome, windows).
1. Drag the image to your desktop -> you'll get a png image rather than a jpg. If you'll right-click to <Save image as..> it will save as jpg.
2. Right-click to <Save image as..> to get the jpg image. Try to upload it as an attachment to your post, you'll get an error "The contents of the uploaded image do not match the file's extension."