Windows error: The client and server cannot communicate, because they do not possess a common algorithm

This error in the Windows agent is due to the windows agent being built using .NET 3.5 which uses TLS 1.0 as a requirement. If you've disabled TLS 1.0 on your system the agent won't be able to post payloads back to us so you'd need to enable TLS 1.0 to resume postbacks. Please contact support if you have any questions.