Stuck on Database Update Required after downgrading to 4.9.9 from backup

You are facing the issue due to the different database versions. Please, follow this steps to fix the issue:

  1. Head to /wp-include/ folder.
  2. Open the version.php file.
  3. Find the value for $wp_db_version.
  4. Open your database. Find wp_options.
  5. Use the following line to identify the value of db_version:

    SELECT option_value FROM yourdatabase.wp_options WHERE option_name="db_version";
    

The values of $wp_db_version and db_version must be the same. Make sure that you make the change in the version.php file, but not the database.