A warning is displayed in the Chrome console window regarding your certificate
You can achieve this using OpenSSL. (Mac OSX includes OpenSSL within Terminal.app)
SHA is a popular hashing algorithm used by the majority of SSL certificates. As computing power has increased the feasibility of breaking the SHA1 hash has increased.
This usually means the implementation of SSL on your server is not correct. The error is usually caused by a server side problem which the server administrator will need to investigate.
This message is sometimes displayed when accessing an SSL page via a proxy (including our own payment page PayPal).