Symptoms

Webmail shows blank page.

The following error can be found in /var/log/httpd/error_log

[Wed Jun 04 02:07:05 2014] [warn] [client 1.2.3.4] mod_fcgid: stderr: PHP Fatal error:  Exception thrown without a stack frame in Unknown on line 0, referer: https://webmail.example.com/login.php
[Wed Jun 04 02:07:06 2014] [error] [client 1.2.3.4] File does not exist: /usr/share/psa-horde/favicon.ico

Cause

Horde database corruption.

Resolution

1. Back up Horde database and its directories:

   # cp -pr /etc/psa-webmail/horde/ /etc/psa-webmail/horde_back
   # cp -pr /usr/share/psa-horde/ /usr/share/psa-horde_back
   
   # mysqldump -u admin -p`cat /etc/psa/.psa.shadow` horde > ~/horde_support.`date +%F_%H:%M`.sql
   

2. Remove Horde using Plesk autoinstaller

3. Log in to MySQL and drop Horde database:

    mysql> drop database horde
   

4. Install Horde using Plesk autoinstaller