Issue with pubkey file during EMS Migration

[rsm]

Hi

I'm trying to migrate from EMS 7.2.5 to 7.4. I have gone through all the steps in the Admin guide and have now hit a brick wall. 

I am getting an error "Authentication (publickey) failed" and "encountered RSA key, expected OPENSSH key" and the migration is failing. I found this article at  https://community.fortinet.com/t5/FortiClient/Troubleshooting-Tip-Getting-an-error-when-performing-E... which did help with another error I had. However, the article just says to the generate the public key, which I have done and re-done several times with no effect. 

Has anyone had this issue? Can anyone help please?

Thanks

Roy