systemd-tmpfiles-setup.service が failed 状態となるのは何故ですか？

Issue

• systemd-tmpfiles-setup.service は開始するときに失敗します。
  ログの例は以下です。

  systemd[1]: Started Import network configuration from initramfs.
  systemd[1]: Starting Create Volatile Files and Directories...
  systemd-tmpfiles[982]: [/usr/lib/tmpfiles.d/mariadb-galera.conf:1] Unknown user 'mysql'.
  systemd-tmpfiles[982]: [/usr/lib/tmpfiles.d/mariadb-galera.conf:2] Unknown user 'mysql'.
  systemd-tmpfiles[982]: [/usr/lib/tmpfiles.d/mongodb.conf:3] Unknown user 'mongodb'.
  systemd[1]: systemd-tmpfiles-setup.service: main process exited, code=exited, status=1/FAILURE
  systemd[1]: Failed to start Create Volatile Files and Directories.
  systemd[1]: Unit systemd-tmpfiles-setup.service entered failed state.
  systemd[1]: Starting Security Auditing Service...