I was able to reproduce this issue. The problem occurs when safe-rm is installed.
How to reproduce using lxc: lxc launch images:ubuntu/18.04 bughunt lxc exec bughunt bash once you're inside the container run: apt install ubuntu-release-upgrader-core safe-rm do-release-upgrade answer yes so that the upgrade initiates when the upgrader reaches "Unpacking libc6:amd64 (2.31-0ubuntu9.9)" it fails with =============== /usr/bin/perl: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory dpkg: error while cleaning up: rm command for cleanup subprocess returned error exit status 127 /usr/bin/perl: error while loading shared libraries: libcrypt.so.1: cannot open shared object file: No such file or directory dpkg: error processing archive /var/cache/apt/archives/libcrypt1_1%3a4.4.10-10ubuntu4_amd64.deb (--unpack): rm command for cleanup subprocess returned error exit status 127 Errors were encountered while processing: /var/cache/apt/archives/libcrypt1_1%3a4.4.10-10ubuntu4_amd64.deb Exception during pm.DoInstall(): E:Sub-process /usr/bin/dpkg returned an error code (1) ========= it appears that a quick workaround is to uninstall safe-rm before upgrading and reinstall afterwards thank you -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1903838 Title: package libcrypt1 1:4.4.10-10ubuntu4 failed to install/upgrade: rm command for cleanup subprocess returned error exit status 127 To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libxcrypt/+bug/1903838/+subscriptions -- ubuntu-bugs mailing list ubuntu-bugs@lists.ubuntu.com https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs