When I try to install a package using tlmgr, e.g.:
$ tlmgr install adjustbox
All I get is
/usr/bin/tlmgr: unexpected return value from verify_checksum: -5.
In tlmgr: unexpected return value from verify_checksum: -5 this error is caused by an out-of-date GPG key for
tlcontrib, but I only have the
main repository according to
tlmgr repository list. I also tried re-downloading the key from CTAN and adding it, but that didn't work.
I'm running Ubuntu 19.10 and TeX Live 2019.
Any help would be appreciated.