"PuTTY key format too new" when using ppk file for PuTTY SSH key authentication

I wanted to connect to my Unix server using SSH keys. For that I had converted my id_rsa file from ./ssh directory to a ppk file using PuTTYgen, but after loading my .ppk key I get this warning:

PuTTY key format too new

If I use my default id_rsa file, then I get error:

OpenSSH SSH-2 private key (old PEM format)

Either way I am getting stuck. Can anyone please help me?

Solution 1:

Easy way to fix this issue, please follow the pictures.
Step1:
Step2:

Solution 2:

If you have a key in the new PPK version 3 format, you can use PuTTYgen to export it to the old PPK version 2 format.

I don't know what Operating System you're using PuTTYgen/PuTTY on, but if it's Microsoft Windows you can set PPK Version 2 by default for PuTTYgen selecting in the app menu:

Key->Parameters for saving key files...->PPK file version: 2.

PuTTYgen: Private Key File Parameters

Solution 3:

I've put newer version of puttygen.exe and pageant.exe in TortoiseGit\bin folder and it works