SFTP Keyfile Format / Connection not possible?

[Leo]

@b-s-ger

I have used WinSCP, it took my private OpenSSH Keyfile (format) and converted it into a Putty format key.

@b-s-ger

Reading private key file "C:\Users-----\Documents\SSH-Identity\Identity.ppk"
Unable to load private key (file format error)

Try using PuttyGen to convert the key file to Putty format. That's what I've used in the past and it worked:

SFTP unable to use this key file

Download PuTTYGen.exe from the PuTTY site, load the key into it, then save it out again in PuTTY's format. That will then work with Opus (and other things based on PuTTY/Pageant).