[21:08] <r0ost3r> hello, found a bug in /var/lib/dpkg/info/phpmyadmin.postinst script. I'm on 20.04lts. have solution. 
[21:20] <r0ost3r> replace 'lighty-enable-mod phpmyadmin auth fastcgi fastcgi-php' with 'lighty-enable-mod phpmyadmin auth fastcgi fastcgi-php || true'. reason: if a mod is already enabled lighty-enable-mod will exit with status 2. preventing avahi_install and desktop_install to execute. 
[21:22] <Jeremy31> r0ost3r: File a bug report and then report your fix