I have a small piece of code which basically impements a HTTP-Client, i.e. it POSTS request and works with re RESPONSE. As long as HTTP is concenerned everthing work well. F
In my case, the protocol and port were not correct while invoking the httpsUrlConnection.
Port and protocol were defined as static class variables. And the step prior to the failed step, was invoking an httpUrlConnection. That method changed the port/protocol to 80/http, but didn't set it back to /https at the end. So eventhough httpsUrlConnection was invoked, it was still using http/80. Once I reset those at the end of the httpUrlConnection method, the error disappeared.