Login fails with error: Could not connect to ssl://localhost:993: Unknown reason

[cmonty14]

Hi,
I have completed setup of self-hosted mailserver based on Dovecot, Postfix and Nginx.
Using a mail client I can receive and send e-mails.

Then I deployed roundcube by installing these Debian packages:
roundcube
roundcube-core
roundcube-pgsql

I can open roundcube WebUI entering this URL: webmail.mydomain.com.

When I try to authenticate using username and password, I get this error message:
[08-Jan-2025 00:51:27 +0000]: <bsmdnvvt> IMAP Error: Login failed for thomas@mydomain.com against localhost from 5.56.204.204. Could not connect to ssl://localhost:993: Unknown reason in /usr/share/roundcube/program/lib/Roundcube/rcube_imap.php on line 211 (POST /?_task=login&_action=login)

The error is related to my roundcube configuration:
$config = [];

// Do not set db_dsnw here, use dpkg-reconfigure roundcube-core to configure database!
include("/etc/roundcube/debian-db-roundcube.php");

// IMAP host chosen to perform the log-in.
// See defaults.inc.php for the option description.
$config['imap_host'] = 'localhost:993';


After modifying this config
//$config['imap_host'] = 'localhost:993';
$config['imap_host'] = 'localhost:143';

the error is not reproducible.

However I want to use IMAPS: 993/tcp that is working with any other mail client.

Please advise how to fix this issue.

THX

[JohnDoh]

The issue is that you are trying to connect to localhost and PHP cannot validate your cert because the hostname and the CN on the cert do not match. see https://github.com/roundcube/roundcubemail/wiki/FAQ#problems-connecting-imapsmtp-server-via-ssltls

Given you are connecting to localhost I don't think you need SSL/TLS because its the local interface.