When I try to download the latest update, I recieve an undefined HTM document.

I'm not seeing that issue, could you provide a screenshot?

Download button work, but the download of v3.1.5 from the updates section does not.

Lorenzo

Download button work, but the download of v3.1.5 from the updates section does not.

strange...  The downloaded HTML code is the umod page  ( https://umod.org/ )
tried with firefox, edge, explorer, chrome and opera with the same result.