Tools like check50 and submit50 rely on git, a popular tool for saving different versions of code, and GitHub, a popular website for saving those versions in the cloud. To push (i.e., save) your code to GitHub using git, it used to be possible to log into GitHub via a command line (as in a terminal window) using a GitHub username and password. As of August 13, 2021, that’s no longer possible, which means you can no longer use check50 or submit50 using your GitHub username and password either.

But you can still use check50 and submit50! You just need to log in a bit differently, either using SSH or a personal access token. Odds are you’ll find SSH more convenient.

See https://cs50.readthedocs.io/github/ for all details.