update-torbrowser is broken in the whonix-ws-16 template as of tor browser 12.0. This problem appears to be due to a Tor project change in URLs. The latest files are now located in the following directories:
update-torbrowser
https://dist.torproject.org/torbrowser/12.0/ http://scpalcwstkydpa3y7dbpkjs2dtr7zvtvdbyj3dqwkucfrwyixcl5ptqd.onion/torbrowser/12.0/
https://dist.torproject.org/torbrowser/12.0/
http://scpalcwstkydpa3y7dbpkjs2dtr7zvtvdbyj3dqwkucfrwyixcl5ptqd.onion/torbrowser/12.0/
Confirmed. This issue has been resolved. An updated tb-updater package is available in all repositories. Will be fixed after updates.
(Whonix is based on Kicksecure.)
For reference: