Failed the authenticate request. ; System.Security.Cryptography.CryptographicException: The parameter is incorrect.

When testing a connection to a Communications Agent or when starting a Job, it's possible to receive the following error:

Failed the authenticate request. ; System.Security.Cryptography.CryptographicException: The parameter is incorrect.;

SureSync MFT utilizes dual encryption on credentials. The final encryption pass is done with the self-signed certificate from the machine in question. This ensures that the only machine that can decrypt the credentials is that specific remote agent. 

If anything happens to the self-signed certificate that the Communications Agent generates such as the certificate being deleted and recreated or expiring, this message will occur because the remote agent no longer can decrypt the credential.

To solve the issue, launch the SureSync MFT Desktop and do the following:

1. Expand Computers in the left-hand tree view and locate the problem agent machine.
2. On the General tab of that Computer, re-enter the credential to access the machine.
3. Click Apply.
4. Click on the 'Test Connections to Agent' button and confirm the connection is now successful.