imagecreatefromjpeg() is a GD2.0 predefined function, and if this is coming up as undefined, then you have an error in your GD installation, or maybe JPG support is not enabled for GD.
Do as I have instructed to a user in this previous post:
https://vborg.vbsupport.ru/showthrea...911#post360911
Then make sure JPG/PNG is enabled, and that PHP on the server is being started with GD support.