I found Migration Zammad to new Server: uninitialized constant ActiveRecord - #4 by tortyl
and tried as root user:
zammad run rails r ‘Cache.clear’
but I get
Please specify a valid ruby command or the path of a script to run.
Run 'bin/rails runner -h' for help.
undefined local variable or method `‘Cache' for main:Object
This is the package “zammad=4.0.0-1623071600.c99fb5c5.focal” installation on Ubuntu.