What might cause logins to work locally yet not in deployed environment?

Question

We're getting a 404 (or a Craft 'page not found' error) with this path on the remote server:

http://foo.example.net/admin/actions/users/login

Same database using remote mySQL. Local logins work fine.

Craft CMS 2.6.2989

Answer 1

Crikey...

/admin/actions/users/login 404

https://twitter.com/nystudio107/status/895726366477344772

Forge!

Answer 2

Yeah, that's a fun one I ran into. The server configs here are known to work with Nginx & Craft CMS 2.x & 3.x: Nginx-Craft