When searching in webmail, nothing is shown. A small red error appears after some time.
Dovecot reads from its index files when it searches emails in webmail. The issue that webmail exhibits, in this case, may be caused by a corrupted Dovecot index cache.
Please note, in the following examples, you should replace cpuser with the cPanel user you are working with, and email@example.com refers to an email account on your server.
To address this, if you're using maildir for storage, you can remove the Dovecot Index files with the following:
/scripts/remove_dovecot_index_files --user cpuser
You can also index a specific user's inbox using the doveadm command:
doveadm index -v -u firstname.lastname@example.org INBOX
If running Solr:
/scripts/rescan_user_dovecot_fts --user cpuser
If the above does not resolve the issue, there is another similar error that must be corrected by moving and rebuilding the user SQLite database: