Resolved

Symptoms

This error can happen on some server setups using a caching layer like APC.

Workaround

First solution: Access the hosting administration and try clearing the server’s cache, if applicable.

Second solution: Apply the following patch in the sitepress-multilingual-cms/classes/language-switcher/class-wpml-ls-templates.php file, on line 303:

Replace:


if ( ! $template->is_path_valid() ) {

With:


if ( ! method_exists( $template, 'is_path_valid' ) || ! $template->is_path_valid() ) {