package libcrypt1 (not installed) failed to install/upgrade: rm-Befehl zum Aufräumen subprocess returned error exit status 127

Just started "do-release-upgrade" on a 18.04 server, install aborts and system seems not to be accessible anymore, tried ssh port 1022, in vain.

ProblemType: Package
DistroRelease: Ubuntu 18.04
Package: libcrypt1 (not installed)
ProcVersionSignature: Ubuntu 4.15.0-136.140-generic 4.15.18
Uname: Linux 4.15.0-136-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.23
Architecture: amd64
Date: Tue Mar 9 15:44:58 2021
ErrorMessage: rm-Befehl zum Aufräumen subprocess returned error exit status 127
Python3Details: /usr/bin/python3.6, Python 3.6.9, python3-minimal, 3.6.7-1~18.04
PythonDetails: /usr/bin/python2.7, Python 2.7.17, python-minimal, 2.7.15~rc1-1
RelatedPackageVersions:
 dpkg 1.19.0.5ubuntu2.3
 apt 1.6.12ubuntu0.2
SourcePackage: libxcrypt
Title: package libcrypt1 (not installed) failed to install/upgrade: rm-Befehl zum Aufräumen subprocess returned error exit status 127
UpgradeStatus: Upgraded to bionic on 2021-03-09 (0 days ago)