Issues Creating Push Mirror to GitHub

Hello,

I’m having an issue creating a push mirror to github from gitlab.com. I’ve generated a new ssh key (ecdsa) for this which I added as a deploy key with write access in github. When I try to use this key as the host key for the mirror it fails to sync with the following error:

13:get remote references: create git ls-remote: exit status 128, stderr: “No ECDSA host key is known for github.com and you have requested strict checking.\r\nHost key verification failed.\r\nfatal: Could not read from remote repository.\n\nPlease make sure you have the correct access rights\nand the repository exists.\n”.

On a local system this would seem like I need to update a known_hosts file, but I have no idea what this would mean in this context.

I have noticed a couple of oddities:

  1. I still get the above ECDSA specific error even if I use an RSA key
  2. The public key that I get from clicking the “Copy SSH public key” button is not the same one I provided and in fact looks like an RSA instead of the ECDSA

Thanks in advance for any help you can provide!