"error" when pressing Login

[[CQFF]Richie]

Hi everyone,

I've got a super weird problem that I'm not even sure where to start with.  When I go to my forum and click on log-in at the top, I get a dialog that simply says error.  I've attached a screenshot.  I am running 2.1.4.

When I click on Sign Up, then go back and click Log In, it lets me log in.

However, when I log out, it reverts back to this weird error.

[Diego Andrés]

You'll find the same issue (and solutions), in this other topic: https://www.simplemachines.org/community/index.php?topic=583922.0