HTTPS hostname wrong: should be <sub.domain.com>. What causes this?

I am getting this 'HTTPS hostname wrong:' error when trying to connect to a server using https. My url looks something like this ``` https://sub.domain.com/tamnode/webapps/app/servlet. ``` I connect using the following code ``` // Create a URLConnection object for a URL URL url = new URL(requestedURL); HttpURLConnection.setFollowRedirects(false); // connect connection = (HttpURLConnection) url.openConnection(); connection.setDoOutput(true); connection.setRequestProperty("User-Agent", USER_AGENT); //$NON-NLS-1$ OutputStreamWriter wr = new OutputStreamWriter(connection .getOutputStream()); ``` but then get an error ``` IOException: HTTPS hostname wrong: should be <sub.domain.com>. at sun.net.www.protocol.https.HttpsClient.checkURLSpoofing .... ``` This is code which has worked in the past but no longer. There have been some changes to the system architecture but I need to get more data before approaching those responsible. What can cause this error? Can I turn off the URLSpoofing check?