cPanel Webmail Not Working? Fix Roundcube, Horde & Squirrelmail Issues

Open a browser and navigate to each client for an affected account:

https://mail.yourdomain.com/roundcube
https://mail.yourdomain.com/horde
https://mail.yourdomain.com/squirrelmail

If Roundcube returns a 500 but Horde loads fine, the issue is Roundcube-specific (usually a database problem). If all three fail, the issue is at the service layer (Dovecot/Exim down or SSL misconfigured).

In cPanel, go to Metrics → Errors and look for entries in the last 30 minutes. Common indicators:

• PHP Fatal error: Uncaught PDOException — Roundcube database corrupt
• IMAP connection to localhost:143 failed — Dovecot not listening
• SSL: error:14094416 — SSL certificate mismatch on mail port

Go to WHM → Home → Restart Services. Click Mail Server (Exim) and then IMAP Server (Dovecot). Wait for each restart to report "OK".

# Restart Exim
/scripts/restartsrv_exim

# Restart Dovecot
/scripts/restartsrv_dovecot

# Confirm both are listening
ss -tlnp | grep -E ':110|:143|:993|:995|:25|:465|:587'

Expected output shows Dovecot listening on 143 (IMAP) and 993 (IMAPS), Exim on 25 and 587.

tail -100 /var/log/exim_mainlog | grep -i "error\|fail\|panic"

Look for certificate path errors or port conflicts. A common culprit is a hostname mismatch between Exim's configured FQDN and the SSL cert's CN.

# Replace cpanel_user, domain.com, and emailuser with real values
cd /home/cpanel_user/etc/domain.com/

# Rename the corrupt DB to a backup
mv emailuser.rcube.db emailuser.rcube.db.bak

# If a timestamped backup exists, use it:
# ls -lt emailuser.rcube.db.* — pick the most recent
# mv emailuser.rcube.db.1716900000 emailuser.rcube.db

Roundcube recreates the database automatically on next login. The user loses saved preferences and address book entries but regains access to all email.

In WHM, go to Email → Repair a Roundcube Installation and click Repair. This reinstalls Roundcube and migrates the database schema to the current version — useful after cPanel upgrades that change the Roundcube version.

# Run the built-in Roundcube repair script as root
/usr/local/cpanel/bin/updateuserdomains
/scripts/update_mailman_cache
/scripts/repair_roundcube --force

# Navigate to the mail directory for the affected account
cd /home/cpanel_user/mail/domain.com/emailuser/

# Rename the main index files
mv dovecot.index dovecot.index.bak
mv dovecot.index.cache dovecot.index.cache.bak
mv dovecot.index.log dovecot.index.log.bak

# Do the same for subfolders (Sent, Trash, Spam)
for dir in .Sent .Trash .Junk .Spam; do
  [ -d "$dir" ] && mv "$dir/dovecot.index" "$dir/dovecot.index.bak" 2>/dev/null
  [ -d "$dir" ] && mv "$dir/dovecot.index.cache" "$dir/dovecot.index.cache.bak" 2>/dev/null
done

Dovecot rebuilds indexes automatically on next login. The rebuild may take 10–30 seconds for large inboxes — warn the user before they panic at a slow load.

doveadm index -u emailuser@domain.com INBOX
doveadm index -u emailuser@domain.com '*'

Run this as root. The second command reindexes all folders including Sent and Trash.

In WHM, go to MultiPHP Manager → System PHP Version. Roundcube requires PHP 7.4 or higher. If the system PHP is set to 5.6 or 7.0, upgrade it.

chmod 755 /usr/local/cpanel/base/3rdparty/roundcube
find /usr/local/cpanel/base/3rdparty/roundcube -type f -exec chmod 644 {} \;
find /usr/local/cpanel/base/3rdparty/roundcube -type d -exec chmod 755 {} \;

# Temporarily rename to isolate the issue
mv /usr/local/cpanel/base/3rdparty/roundcube/.htaccess    /usr/local/cpanel/base/3rdparty/roundcube/.htaccess.bak

Reload the webmail URL. If it now loads, a custom rewrite rule in .htaccess is conflicting with Roundcube's own rules.

rm -rf /usr/local/cpanel/base/horde/tmp/*
rm -rf /usr/local/cpanel/base/horde/static/cache/*

In WHM, go to Email → Repair a Horde Installation and click Repair. This resets the database tables and refreshes configuration files.

tail -50 /usr/local/cpanel/base/horde/log/horde.log