If this is a new SFTP setup or the 3rd party has made changes to the certificate then you first need to connect to the 3rd party using putty.exe.
The instruction below will need to be run from the server the task server runs on.
Run putty.exe which can be found in your 3.4.0/proclaim/3rdParty folder.
Type Open followed by your connection details.
Select Yes when prompted to download the security fingerprint.
If you need further assistance, please raise a new case online and reference the title of this article.