The debian package installed from PPA cant be uninstalled properly on Ubuntu 18.04:
$ LC_ALL=C sudo apt autoremove --purge mympd
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages will be REMOVED:
mympd*
0 upgraded, 0 newly installed, 1 to remove and 195 not upgraded.
After this operation, 0 B of additional disk space will be used.
Do you want to continue? [Y/n]
(Reading database ... 463475 files and directories currently installed.)
Purging configuration files for mympd (5.5.2-1) ...
userdel: user 'mympd' does not exist
groupdel: group 'mympd' does not exist
dpkg: error processing package mympd (--purge):
installed mympd package post-removal script subprocess returned error exit status 6
Errors were encountered while processing:
mympd
E: Sub-process /usr/bin/dpkg returned an error code (1)
The debian package installed from PPA cant be uninstalled properly on Ubuntu 18.04: