I've been moving different platforms to HTTPS. Despite of some minors problems, you have to take care about all the content embed in the website (videos, iframes, etc.) that is not https. All of these content will be not available when you switch your website to https.
So, before to do that, list all the content non https and try if it works with using https protocol.
This is very true, auditing before move makes fixing all these mixed content issues a lot easier. There's some tools in the above guide that can help but there's not really a perfect solution yet.