My issue turned out to be that the Bionic Beaver (18.04) libdouble- conversion1 package does not contain the .so files, but the Artful ones do. I downloaded the Artful package and now the thg UI starts correctly.
http://archive.ubuntu.com/ubuntu/pool/main/d/double-conversion /libdouble-conversion1_2.0.1-4ubuntu1_amd64.deb https://ubuntu.pkgs.org/17.10/ubuntu-main-amd64/libdouble- conversion1_2.0.1-4ubuntu1_amd64.deb.html -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1770190 Title: Tortoise HG UI doesn't start after Ubuntu 18.10 upgrade To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/tortoisehg/+bug/1770190/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs