- Status
- Resolved
Overview of the issue
We have noticed that there are some customers reporting a fatal error on activating WPML
PHP Fatal error: Call to undefined method Composer\Autoload\ClassLoader::setPsr4() in .../wp-content/plugins/sitepress-multilingual-cms/embedded/composer/autoload_real.php on line 33
This issue happens from one of your other plugins using an outdated version of Composer, where the autoloader does not support setPsr4() method.
The problem happens when a plugin with such old version bundled is initialized before WPML plugin.
You can read more details here: https://github.com/composer/composer/issues/2553
Workaround
To fix the issue you must first find the offending plugin: you can do it by disabling all plugins, except WPML, and then re-activating them one by one.
Then it is advisable that you seek updated version of that plugin: if the issue does not get resolved, contact the author and let him know about the issue.