How to fix "The following module is missing from the file system..." warning messages
If we have this warning message in our drupal 8 is as easy as running a few lines of code:
drush sql-query "DELETE FROM key_value WHERE collection='system.schema' AND name='module_name';"
Let's run this line in our console, simply add the name of the module that is causing us the error.
$query = \Drupal::database()->delete('key_value') ->condition('collection', 'system.schema') ->condition('name', 'module_name') ->execute();
As with the previous example, we will replace module_name with the name of the affected module.
You need to have the Devel module enabled and run this line in /devel/php