/admin/actions/users/login 404 When trying to login to my live env on craft, I get the following error in the javascript console.

[Error] Failed to load resource: the server responded with a status of 404 (HTTP/2.0 404) (login, line 0)


This only happens in the live environment, which is weird because the DB and front-end code are synced between local and live. There is also a staging website where the login page works.
What server provisioner are you using? Forge? Something else? If it's Forge, it's most likely this:

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

Also here are some Nginx configs (with Forge examples) that are known to work with Craft CMS 2.x and 3.x: Nginx-Craft