Version 2.2.2 has the following issue:
[23-Dec-2020 15:48:53 UTC] PHP Warning: call_user_func() expects parameter 1 to be a valid callback, no array or string given in /home1/<your_username>/public_html/wp-content/plugins/restaurant-reservations/includes/template-functions.php on line 211
Issue was on the following line on wp-content/plugins/restaurant-reservations/includes/template-functions.php:
call_user_func( $field['callback'], $slug, $field['title'], $field['request_input'], $callback_args );
Temporary Fix:
Replace the plugin files with your old version (Version 2.1.19) in the following directory:
<your_website>\wp-content\plugins\restaurant-reservations
My guess on the issue:
They have added some new fields in the plugin. So, it needs to be fixed. I saw a new "Message" field.
