Reported for: WPML Multilingual CMS 3.7.1
Resolved in: 3.8.0
Overview of the issue
If you downgrade from WPML 3.8.x to WPML 3.7.1 or lower, you may get the following error:
PHP Fatal error: Call to undefined method WPML_Notice::must_reset_dismiss() in /wp-content/plugins/sitepress-multilingual-cms/classes/notices/class-wpml-notices.php on line 111
The problem is in the old versions of WPML and you can fix it by going to the options table and deleting the wpml_notices key.
You can use a command similar to the following one:
DELETE FROM wp_options WHERE option_name = 'wpml_notices';