Problem/Motivation
I am using Drupal 10.2.5 and PHP 8.3.6 on Ubuntu 22.04.
My website suddenly no longer displays properly since last night and only displays the following message:
Drupal\Component\Plugin\Exception\PluginNotFoundException: The "" plugin does not exist. Valid plugin IDs for Drupal\Core\Display\VariantManager are: in Drupal\Core\Plugin\DefaultPluginManager->doGetDefinition() (line 53 of core/lib/Drupal/Component/Plugin/Discovery/DiscoveryTrait.php).
Those "varying words" were initially "text_default" and became "language", "block_page", etc. when I tried to resolve the issue according to past posts here.
Steps to reproduce
Many past posts here on similar issues have been read. They were basically related to Drupal 8 or 9. I am now using Drupal 10. Those issues have been closed for quite some time. The solutions posted have been tried by me but without success. Such solutions are: using drush updatedb, drush eval "drupal_flush_all_caches();", drush cr, etc. or editing the codes.
I had restored once the website and mysql database based on 7 April 2024 backups. It worked.
But after I have done composer update -W, drush updatedb, and drush cr, the above message appears again.
Proposed resolution
I guess that the updates since 7 April 2024 might be the cause of the problem.
I would restore the old backup again for temporary use.
I am looking for help to resolve the issue.
Thanks!