Apache - Reverse Proxy to a backend server running https, warning message

If you ever set some https reverse proxy server to hit a backend through https as well, i.e. set something like (in Apache):

ProxyPass /abc https://abc.somewhere.com

You will likely get some browser warning complaining that the names don't match. To prevent this, simply request your backend SSL certificate with a subject alternative name = your proxy server SSL name, along with your backend common name (here abc.somewhere.com). Then users won't get warnings in their browser.