PHP 7.4.3 was released on 20th February 2020.

It has resolved the bug in PHP 7.4.2 that broke WordPress authentication for usernames with spaces.

For more information, see:

• User authentication broken for usernames that include spaces (PHP bug #78929)
• Bug #78929 plus signs in cookie values are converted to spaces
• Bug #79174 setcookie() encodes space as `+`, but $_COOKIE no longer decodes them

PHP 7.4.2, the most current version, was released on the 23rd January 2020.

A bug in this version of PHP breaks WordPress authentication for usernames with spaces. That is, if a user attempts to log into their account via the WordPress login page, it will just display the login form again. It makes no difference if the user enters their username or their email address.

The immediate workaround is to downgrade to PHP 7.4.1 and then upgrade to PHP 7.4.3 once it has been released.

For more information, see:

• User authentication broken for usernames that include spaces (PHP bug #78929)
• Bug #78929 plus signs in cookie values are converted to spaces