Warning: hash_equals(): Expected user_string to be a string, null given in .../administrator/components/com_civicrm/civicrm/CRM/Contact/BAO/Contact/Utils.php on line 232
When looking at a contact's profile via the front end under Joomla I get:
Warning: hash_equals(): Expected user_string to be a string, null given in …/administrator/components/com_civicrm/civicrm/CRM/Contact/BAO/Contact/Utils.php on line 232. I saw this under 5.11.0, and now under 5.12.0. Without a Joomla demo site I can't reproduce it - the demo site is running 5.5.3, and doesn't have a view profile menu item in the front end.
See also https://civicrm.stackexchange.com/questions/28768/hash-equals-expected-user-string-to-be-a-string-null-given-in-contact-bao-co; a question that hasn't been answered. I have been looking at code to avoid the warning.
I realise that Joomla front-end errors are a low priority.