People who click on an opt-out URL in our civimail get an error screen like "Sorry, due to an error, we are unable to fulfill your request at the moment." The ReportError extension captures a backtrace that I stored on pastebin here. I verified that this error is coming from real humans trying to opt out, not from bots.
This part is confusing:
Array ( [type] => 2 [message] => fopen(api/v3/Country/Getfields.php): failed to open stream: No such file or directory [file] => /home/user/wordpress/wp-content/plugins/civicrm/civicrm/CRM/Utils/File.php [line] => 417 )
Because in fact there is no file at api/v3/Country/Getfields.php, trying to fopen it causes an error. Can anyone decipher this for me?
Edit: This is on Civicrm 5.36.1 and Wordpress 5.7.2.