I also have this issue but it is with the audit plugin, and it impacts MariaDB upgrades over apt, rather than an install of MariaDB from scratch.
I receive this message in the syslog from mariadb-server-10.3.postinst Installation of system tables failed! ... In /var/log/mysql/error.log, I see this: [ERROR] mysqld: Can't open shared library '/usr/server_audit.so' (errno: 22, cannot open shared object file: No such file or directory) [ERROR] Couldn't load plugins from 'server_audit.so'. [ERROR] /usr/sbin/mysqld: unknown variable 'server_audit=FORCE_PLUS_PERMANENT'[ERROR] Aborting The database server continues to function correctly after the service starts. The audit plugin is functional outside of the postinst script. This issue has happened for about a year or two and I never noticed any issues otherwise. I was concerned about a new patch adding newly required system tables failing, such as with an upgrade from Buster to Bullseye, etc. I am unsure if this is the exact same issue as this big. If not, let me know and I can open a new bug report. On a mostly normal Buster: dpkg -l | grep maria ii libmariadb3:amd64 1:10.4.14+maria~buster amd64 MariaDB database client library ii mariadb-client-10.3 1:10.3.39-0+deb10u2 amd64 MariaDB database client binaries ii mariadb-client-core-10.3 1:10.3.39-0+deb10u2 amd64 MariaDB database core client binaries ii mariadb-common 1:10.4.14+maria~buster all MariaDB database common files (e.g. /etc/mysql/conf.d/mariadb.cnf) ii mariadb-server 1:10.3.39-0+deb10u2 all MariaDB database server (metapackage depending on the latest version) ii mariadb-server-10.3 1:10.3.39-0+deb10u2 amd64 MariaDB database server binaries ii mariadb-server-core-10.3 1:10.3.39-0+deb10u2 amd64 MariaDB database core server files ii mysql-common 1:10.4.14+maria~buster all MariaDB database common files (e.g. /etc/mysql/my.cnf)