Unfortunately, I’ve just downloaded the current version today and I’ve run into this issue. Strangely enough, adding the Wordfence plugin broke the 2FA plugin I had previously been using (mini-orange). I was unable to login to my admin account and had to delete the 2FA plugin via FTP before I could log back in. I got a time error when trying.
OK, so I found an answer elsewhere. I downloaded a fresh install of WordPress and, via ftp, replaced everything except wp-config.php and the folder/contents of wp-content. Back up and running.
Thanks Janet! I had just installed a few new plugins, and upon disabling, the problem seems to have disappeared. Luckily the plugins weren’t essential, so I’ve deleted them.