Github SSH keys verification error?

Question

It was still usable two months ago, but recently it has been unable to push. Is this the reason why the ssh key has expired?

Answer 1

From my personal experience, there may be the following reasons:
1. You changed the computer. There is no .ssh folder in your current computer, and you cannot use the files here for encryption verification.
2. The proxy is hung up. The specific reason is unclear.