Trailing slash in Base Page URL resulting in 404
I'm not exactly sure where this bug showed up, but it was working before upgrading to WordPress 5.5/5.5.1 on CiviCRM 5.27.x. After upgrades, public pages using the Base Page resulted in 404 errors. Pages containing shortcodes continue to work correctly. Removing the trailing slash from the Base Page URL, wp-admin/admin.php?page=CiviCRM&q=civicrm/admin/setting/uf&reset=1, immediately fixed the problem and the pages loaded as expected. (No cache clearing was necessary. Every form of cache clearing had been tried before making this change with no change in the results.) Adding the trailing slash back in resulted in 404's once again. This behavior was confirmed by Kevin. Here's the chat link with possibly a little more information: https://chat.civicrm.org/civicrm/pl/7rum7yt6jjgbjkw3ust4zmpfmh