Git push failing with Fatal: HttpRequestException encountered

Are you using Windows and GitHub? This is because GitHub disabled weak encryption, specifically TLS v1.0 and v1.1

Using the Git Credential Manager for Windows will fix this. You can download the latest version.

Felipe's answer is correct. Just wanted to mention that updating Git for Windows also works.

It updates Git Credential Manager, Git itself and all other bundled software at the same go.

(Not enough reputation to comment so had to add this as an answer instead.)

You can download and reinstall the latest source release of Git from https://git-scm.com/
I am using windows and it worked for me.