Load key "privkey.ppk" invalid format

Question

What have I done:
I'm trying to connect to my remote server with private key with

ssh -i privkey.ppk root@ip

But it's returning an error.
Error message:

Load key "privkey.ppk": invalid format
root@ip: Permission denied (publickey).

Expected result:
I should be able to login into my remote server with ssh key.

Key file content:

PuTTY-User-Key-File-2: ssh-rsa
Encryption: aes256-cbc
Comment: rsa-key-20181019
Public-Lines: 6
some lines
Private-Lines: 14
some lines
Private-MAC: some letters

OS: Ubuntu 18.04

(p.s:

1. I'm using the same key in putty, termius to login into my remote server and its working fine
2. Ansible ping cmd also returning the same result)

Answer 1

This key is generated by PuTTYgen software. To use it in linux you should start PuTTYgen, load the key (File->Load private key) and then export it as OpenSSH key ( Conversions->Export OpenSSH key)

Answer 2

My PPK was in putty PPK format I had to convert into OpenSSH format.
I converted .ppk to OpenSSH using this answer, now I'm able to connect.

puttygen id_dsa.ppk -O public-openssh -o id_dsa.pub