If you see the "Couldn’t load private key(unable to open file)" error message in PuTTYgen when you try to load a private key, then you should try the
OK, I think I know what the cause of the problem is: The private key is in the new OpenSSH format, which libssh2, the library I am using for SSH, doesn't support. libssh2 only supports RSA and DSA keys, and they must be in the old format (PEM). ...
debug1: Offering public key: RSA SHA256:iq/xxxxxxxxxxxxxxx /home//.ssh/id_rsa debug1: Authentications that can continue: publickey,password,keyboard-interactive debug1: Trying private key: /home/user/.ssh/id_dsa debug1: Trying private key: /home/user/.ssh/id_ecdsa debug1: Trying private...