Error 400 in Roblox, Explained In a nutshell, Error 400 crops up due to a number of system-wide reasons, but they largely pertain to issues with the Roblox online servers.

Clear your DNS cache, which should fix the 400 Bad Request error if it's being caused by outdated DNS records that your computer is storing.

It's called a 400 error because that's the HTTP status code that the web server uses to describe that kind of error. A 400 Bad Request can happen for many reasons.