Board Thread:Support Requests - Getting Technical/@comment-896291-20140625091619/@comment-452-20140625205734

Lady Lostris, Lily Ford said nothing about attempting to overwrite a file.

What has happened is that the "png" is actually a jpg which has been renamed to .png

Browsers and most image software don't generally care whether the extension matches the mime type, as they use the file header rather than the extension when reading the file.

Mediawiki, on the other hand, checks the mime type against the extension, and requires them to match.

Luckily, mediawiki gives you a hint in the error message "File extension ".jpg" does not match the detected MIME type of the file (image/png)." - usually you can see in the error message what you need to change.

Does your error message actually say $1 and $2? because it's supposed to fill those values in.

Edit: I just attempted to upload a png renamed to jpg here, and the values were correctly filled in.