Though I have made no changes to the site other than normal WP, plug-in, and GP Theme updates, the widget admin screen has changed and does not work properly. The widget layout looks completely different now and at the top of the screen on the widget page, when logged into my WP admin, I get these messages in a red background such as “The “custom_html” block was affected by errors and may not function properly. Check the developer tools for more details.” No idea what that means. Any ideas how to restore or fix? Thanks.
what you’re seeing is the new Block Widget editor that WP introduced in 5.8.
If you want to use the Classic widget area then this document provides a PHP Snippet to do that:
I understand the PHP snippet that you provided to disable the new block editor. But what do I do if I want to use the new feature? Do I have to remove the current widgets and re-add them? A brief overview of the process would be helpful.