I saw a ticket the other day where a customer received this error from Horde when trying to expand items on the left pane of the interface: Fatal error: Cannot use string offset as an array in /www/horde/lib/Horde/Block/Layout/Manager.php on line 389 It turns out that Plesk 8.1.1 bundles Horde 3.1.3 which has an occasional bug within the interface. Upgrading to Plesk 8.2.0 corrects the issue as Horde 3.1.4 is installed with the upgrade.
If you’ve used newer versions of Horde with Plesk, you have probably noticed the news feed that runs down the left side of the screen. Depending on the types of e-mails you receive, you may get some pretty odd news popping up on the screen. Luckily, you can remove the news feeds pretty easily. Open the following file in your favorite text editor: /usr/share/psa-horde/templates/portal/sidebar.inc Once the file is open, drop down to line 102 and comment out the entire if() statement (lines 102-117).
There’s a few issues with PHP 5.2.5 and the version of Horde that is bundled with Plesk 8.1.x and 8.2.x. The PHP include paths that appear in the Apache configuration generated by Plesk conflict with the PHP installation, and that causes the Horde webmail interface to segmentation fault. To fix the problem, create a file called /etc/httpd/conf.d/zz050a_horde_php_workaround.conf and put the following inside it: <DirectoryMatch /usr/share/psa-horde> php_admin_value include_path "/usr/share/psa-horde/lib:/usr/share/psa-horde:/usr/share/psa-horde/pear:." </DirectoryMatch> Reload the Apache configuration and your Horde installation should work properly with PHP 5.