Plesk webmail showing blank page

Sometimes on plesk servers http://webmail.domainname.com may give you a blank page. This usually occurs after upgrading the PHP to php 5. This is due to a bug in the version 5.2.5 of PHP that affects the functioning of Horde which is installed by default with the Plesk control panel 8.1.x or 8.2.x.

When you do a tail -f /var/log/httpd/error_log , you will get the following error in the apache error log.

[Mon Dec 17 02:56:33 2007] [error] [client IP] PHP Fatal error: require_once()
[function.require]: Failed opening required ‘Horde/String.php’
(include_path=’/usr/share/psa-horde:/usr/share/psa-horde/pear:.’) in
/usr/share/psa-horde/lib/Horde/Browser.php on line 4

Fix is edit the /etc/httpd/conf.d/zz010_psa_httpd.conf file and replace the current php_admin_value include_path’ php_admin_value include_path “/usr/share/psa-horde:/usr/share/psa-horde/pear:.” ‘ with the following line.

php_admin_value include_path “/usr/share/psa-horde/lib:/usr/share/psa-horde:/usr/share/psa-horde/pear:.”