SSL connection to the server failed

Hi,
After version 13420 on a number of URL monitors I get the following error message:-
"SSL connection to the server failed.
Reason: Peer not authenticated. This exception occurs when the connection made to server URL is not from authenticated client.(This may be due to wrong SSL version, no certificate, the particular cipher suite being used does not support authentication or no peer authentication was established during SSL handshaking)
"

Please can anyone help me to resolve this issue as I cannot upgrade any managed servers till this is fixed.

Thanks

Steve