Drupal 11: admin paths throw 404

Problem/Motivation

When upgrading from 10.5 to Drupal 11.3 I started to get 404 when trying to load /admin/* paths.

Proposed resolution

When checking the table router there are paths that have pattern_outline empty. This causes the 404.

    $sql = "SELECT name, path, pattern_outline FROM {router} WHERE :path LIKE CONCAT(pattern_outline, '%') AND pattern_outline != '/'";

Adding to the clause to not get empty pattern_outline should fix this.

    $sql = "SELECT name, path, pattern_outline FROM {router} WHERE :path LIKE CONCAT(pattern_outline, '%') AND pattern_outline != '/' AND pattern_outline != ''";