Unable to access mail: Warning: Inotify instance limit for user exceeded

Symptoms

• Unable to access a mailbox.

• The following error is shown in /var/log/maillog :

  CONFIG_TEXT: mail16 dovecot: service=imap, user=johndoe@example.com, ip=[203.0.113.2]. Warning: Inotify instance limit for user (UID popuser) exceeded, disabling. Increase /proc/sys/fs/inotify/max_user_instances

Cause

'fs.inotify.max_user_instances' limit is exceeded.

Resolution

1. Connect to the server using SSH.

2. Increase 'fs.inotify.max_user_instances' value with the command:

   # echo "fs.inotify.max_user_instances = 1024" >> /etc/sysctl.conf
   # sysctl -p

3. Check if variable is applied using:

   # /sbin/sysctl -a | grep instances
   fs.inotify.max_user_instances = 1024