puttygen: error loading x.ppk: PuTTY key format too new

Putty saves ssh key in file with .ppk extension. To use the key on Linux systems, you need to convert it to openssh format. When converting ppk file to openssh format, i got error “PuTTY key format too new”.

This error is because the puttygen command is older version. Ubuntu 20.04 comes with older version of puttygen command provided by putty-tools.

The solution is to remove putty-tools package, then install latest version of puttygen from source code.

Remove putty-tools with

Download and install latest puttygen from


As of writing this, latest version of putty is version 0.76

Once installed, you can check version with

You will be able to convert newer version of ppk files to openssh format now.

See Convert PPK file to PEM

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