Why won't Dovecot restart?

Question

linux

Hello! For some reason Dovecot won't restart on Ubuntu 16.04. In the logs /var/mail.log I see:

dovecot: master: Fatal: service(pop3-login) access(/usr/lib/dovecot/pop3-login) failed: No such file or directory

The /usr/lib/dovecot/pop3-login folder is not on my server.
I manually create folders - other similar messages appear.

Feb  2 10:39:55 esk2 dovecot: master: Fatal: service(pop3-login) access(/usr/lib/dovecot/pop3-login) failed: No such file or directory
Feb  2 10:42:49 esk2 dovecot: master: Fatal: service(imap) access(/usr/lib/dovecot/imap) failed: No such file or directory
Feb  2 10:43:25 esk2 dovecot: master: Fatal: service(imap-urlauth-worker) access(/usr/lib/dovecot/imap-urlauth-worker) failed: No such file or directory
Feb  2 10:44:12 esk2 dovecot: master: Fatal: service(imap-urlauth) access(/usr/lib/dovecot/imap-urlauth) failed: No such file or directory
Feb  2 10:44:44 esk2 dovecot: master: Fatal: service(imap-urlauth-login) access(/usr/lib/dovecot/imap-urlauth-login) failed: No such file or directory

Answer 1

Are the packages installed?

dovecot-imapd
dovecot-pop3d

Answer 2

How was the dovecot set? (Your libraries are missing or installed in the wrong place where dovecot expects them to be)