Undefined offset in sitepress.class.php on line 2344

Overview of the issue

In some cases, the following notices is shown on screen on in the log files: Notice: Undefined offset: 0 in /home/ubuntu/websites/types/wp-content/plugins/sitepress-multilingual-cms/sitepress.class.php on line 2344

The issue is most commonly shown on WordPress administration pages, but may appear on the front-end pages as well.

This is caused by a wrong retrieval of the first item of an indexed array, which, in some cases, may not start with 0 (zero) as the index.

A common case is when children pages have been created before parent pages, and editing/creating a new page throws the notice when rendering the parent dropdown selector.

Workaround

The issue will be fixed in the next release of WPML.

Meanwhile, to fix the issue in your installation, follow these steps:

1. Make a backup of your website
2. Download this file and unzip it: you should have now a file called sitepress.class.php
3. Replace sitepress.class.php in your server (it should be in wp-content/plugins/sitepress-multilingual-cms/) with the new one