Unable to update Plesk: debconf: DbDriver “config”: /var/cache/debconf/config.dat is locked by another process

Symptoms

Unable to update Plesk with the following error in /var/log/plesk/install/autoinstaller3.log:

debconf: DbDriver "config": /var/cache/debconf/config.dat is locked by another process.

Cause

The file locked by another process prevents the updates.

Resolution

Note: if direct SSH access to the server is not possible, contact server administrator for further assistance.

1. Connect to the server via SSH;

2. Find the process ID that locks the file from the error message:

   # lsof /var/cache/debconf/config.dat
   COMMAND PID USER FD TYPE DEVICE SIZE/OFF NODE NAME
   frontend 44515 root 4uW REG 252,0 60012 55592027 /var/cache/debconf/config.dat

3. Check the process via the following command:

   # ps auxf | grep 44515
   root 44515 0.0 0.0 60700 2196 pts/0 S+ Feb18 0:00 | _ /usr/bin/perl -w /usr/share/debconf/frontend /var/lib/dpkg/info/postfix.postinst configure 3.1.0-3ubuntu0.2

4. Kill the process.

   # kill -9 44515

5. Install updates again.