Article ID: 116849, created on Aug 21, 2013, last review on Jun 17, 2016

  • Applies to:
  • Plesk 11.0 for Linux
  • Plesk 11.5 for Linux


The following messages are displayed in the Parallels Installer interface before the upgrade:

After the Panel upgrade, the Panel-managed webmail software will require the following PHP versions: RoundCube - PHP 5.2 or later, Horde - PHP 5.3 or later, AtMail - any PHP version. Note that your version of PHP might become incompatible with the Panel-managed webmail afer the upgrade - in this case, you can switch to AtMail or upgrade PHP.

AtMail is not installed on your server. You can install the AtMail webmail before the Panel upgrade. As an alternative, you can install a newer PHP version that will be compatible with your webmail after the upgrade.

The installed PHP version is 5.1.6-39.el5_8

After the upgrade you will not be able to use the Horde webmail because it requires PHP 5.3 or later.

After the upgrade, Horde webmail does not work.


Horde 5.0 comes with Parallels Plesk 11.5 and requires PHP 5.3. If PHP 5.2 or an older version is installed on the server, Horde stops working.


Upgrade PHP to version 5.3 before upgrading to Plesk 11.5:

  1. Go to "Tools & Settings > Updates & Upgrades > Add Components."
  2. De-select "Show only not installed components."
  3. Select "PHP5.3 support" under "Different PHP interpreter versions" and click Continue.

If some hosted websites are not compatible with PHP 5.3, there are two possible solutions:

  1. Upgrade PHP to version 5.3 before or after upgrading to Plesk 11.5, then install an older version of PHP for incompatible websites using the instructions provided in article #116846.

  2. Keep an older version of PHP on the server and uninstall/disable Horde. Use Roundcube, Atmail, or another webmail interface instead.

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