Unable to start Dovecot:Failed at step NAMESPACE spawning /usr/sbin/dovecot: Permission denied

Symptoms

• Dovecot fails to start with the following error in /var/log/syslog file:

  Sep 9 04:06:09 vps1 systemd[6778]: Failed at step NAMESPACE spawning /usr/sbin/dovecot: Permission denied

• Server is running inside LXC container

Cause

AppArmor policies on LXC host server side.

Resolution

Adjust AppArmor policies on LXC host server side: How to enable bind mount inside lxc container

OR

1. Connect to the server via SSH.

2. For the service unit set PrivateTmp to false:

   • For Debian 8 and higher:

     # cat /lib/systemd/system/dovecot.service
     ...
     [Service]
     PrivateTmp=false

3. Reload systemd manager configuration:

   # systemctl daemon-reload

4. Start Dovecot:

   # systemctl start dovecot.service