fulviaL

Problem:
The client is experiencing a critical error when activating the WPML plugin on a subsite in a WordPress multisite environment. The error occurs after following the standard procedure of installing and activating the plugin network-wide, then on the main site, and finally on the subsite. The error manifests as a blank page displaying 'There has been a critical error on this website' during the final steps of the WPML configuration.
Solution:
We identified a syntax error and a fatal error in the WPML plugin files through the debug log provided by the client. The errors were related to incorrect HTML tags and a null object reference in the plugin's upgrade script. To resolve this, we recommended modifying the

AddTranslationManagerCapToAdmin.php

file. The client should change the code from:

get_role('administrator')->add_cap(User::CAP_MANAGE_TRANSLATIONS);

to:

if(get_role('administrator') != NULL){ get_role('administrator')->add_cap(User::CAP_MANAGE_TRANSLATIONS); }

This modification checks if the 'administrator' role exists before attempting to add capabilities, preventing the error.

If this solution does not resolve the issue or seems irrelevant due to updates or different circumstances, we highly recommend checking related known issues at https://wpml.org/known-issues/, verifying the version of the permanent fix, and confirming that you have installed the latest versions of themes and plugins. If problems persist, please open a new support ticket at WPML support forum for further assistance.