Fatal Error: Disconnected: No supported authentication methods available.

I lost so many hours to that little error. Here was the problem:

I followed the steps in this lovely PyCharm tutorial which walks you through creating your ssh key, saving it to a profile, and applying it to your GitHub account. This was successful in getting the terminal working. However, the error noted above was happening when I tried to use PyCharm’s Git integration and pull or push with the GitHub repository.

Inside the Git console of PyCharm the error would appear and I spent hours trying everything, from changing the GIT_SSH environmental variable to setting that same variable inside PyCharm’s environmental variables… because I knew Git and git-bash could do this and worked fine.

Turns out, the problem was PuTTY, which I had installed long before PyCharm. More specifically, an SSH authentication agent called Pageant. The process involved using this SuperUser Tutorial from Mr. Polywhirl. It outlined how to use PuTTYgen to extract my existing keys to a .ppk, save it, apply it to Pageant, then test it with PuTTY before it worked perfectly in PyCharm.

Update: January 27, 2021
Pageant doesn’t like to remember keys or startup on boot, so I had to create a shortcut in Windows Startup folder with the key passed to the tool. Now, on boot, Pageant is loaded as well as the key necessary to push to GitHub.

Anyway, I hope this helps you as well (or future me, if you’re reading this, you’re welcome).