Re: HTTP 500 Internal Server Error

@Sabiine28  Hit Windows key-R, enter "appwiz.cpl" without quotes, and in the File Explorer window that opens, click "Turn Windows features on or off."  On the list of features, is Internet Explorer present, and is the box next to it checked?

The thing is, the launcher is definitely borrowing the resources of some browser, or at least trying to.  If it can't use IE, maybe it's using Chrome or Edge.  It's possible you need to clear the cache for that browser, and it's also possible that the launcher doesn't work correctly with the browser itself.  So I'm not sure whether the answer is to clear your browser's cache or to reenable IE, if it's not already enabled, and let the launcher use that instead.  You may need to try a few different things to get it to work.