This message is sometimes displayed when accessing an SSL page via a proxy (including our own payment page PayPal).
It is caused by Chrome being unable to render the 502/302 proxy response for some sites (Issue 119713).
Check your browsers Proxy settings. If possible remove the proxy and try again.
To change this setting, go to chrome://chrome/settings/
Then Click [Show Advanced Settings]. Scroll down to [Network] and click [Change proxy settings...] Uncheck Automatically Detect.