Thanks for your bug report. First of all, you're not using ubuntu-releaser, but apt.
Secondly, the lock message indicates something else is currently upgrading/installing packages or working the the database (possibly unattended-upgrades installing security updates), you have to wait for those to finish (whatever you do, do NOT delete the lock file, that's a common misconception about how locking works). ** Package changed: ubuntu-release-upgrader (Ubuntu) => apt (Ubuntu) ** Changed in: apt (Ubuntu) Status: New => Invalid -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1789412 Title: i can not upgrade to ubuntu 18 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/apt/+bug/1789412/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs