Just a heads up - today looks like FreeAgent have stopped API access using older SSL3 / TLS1 protocols today. They have been ‘depreciated’ for a while as they have security flaws.
If you keep your libraries up to date then likely you won’t have a problem.
If you’ve got a little admin tool that you built years ago and haven’t kept updated it may suddenly stop working today!
In the Microsoft .NET world something using the .NET framework 4.5 will default to SSL3 / TLS1 and throw errors like
[IOException: Authentication failed because the remote party has closed the transport stream.] ... [WebException: The underlying connection was closed: An unexpected error occurred on a send.]
Solutions include upgrading to later version of .NET, adding a registry fix to force use of TLS1.2 or adding following line in app startup
ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12 | SecurityProtocolType.Tls11 | SecurityProtocolType.Tls | SecurityProtocolType.Ssl3 ;