Similar issue after installing munin on Debian 11.2. Error shows in shell:
aideinit -f -y Running aide --init... ERROR: /etc/aide/aide.conf.d/31_aide_munin-nodes (stdout):1: unexpected character: '/' (line: '/var/cache/munin/www/localdomain\n/(index\.html|localhost\\.localdomain/[-_[:alnum:]]+\.(png|html))$ f VarFile/var/lib/munin/localdomain/localhost\\.localdomain\n-.*\.rrd$ f VarFile/@@{RUN}/munin/munin-(update|datafile|localdomain-localhost\\.localdomain|limits)\.lock$ f VarFile') AIDE --init return code 17 - - - munin 2.0.67-3 aide 0.17.3-4+deb11u1 aide-common 0.17.3-4+deb11u1