FileMaker emailed an alert to cloud customers warning that they may not be able to login to their FM Cloud console using valid credentials. My cloud 17 client did not have a problem logging in, but my cloud 16 client did.  WARNING: Their support team is requesting administrators to send an UNENCRYPTED EMAIL containing the private key file to resolve this issue. But, they do have an FTP-TLS method for delivering this file. Make sure to ask for this info if you are also locked out of your server. Now, I'd rather not send them the private key file period since it is no longer private, but there seemed to be no option. Any idea what is going on and why they are requesting this unusual step?

I've had to do this for two FM Cloud 16 instances, seems like there is a bug which just prevents login for these older versions. Upgrading the FM Cloud instance (whilst you can still login) resolves the issue, but once you have the issue, you have to do as they ask. They need RDP access to the instance and the private key.

It pretty embarrassing for them really, and it takes over 24 hours to resolve in my experience.