I purchased a copy on Steam over the weekend, as it was only £13.99 for both ED and Horizons (and some free paint jobs). I hit this error.
So, I tried starting from outside steam, this worked (no update error) but gave me only the ability to play a demo, and no obvious way to input the steam codes. You can view these from your steam account, but offhand I don't know where they hang out.
I then went to that link above, pasted in the LINKED commander's e-mail address, then the codes and it all worked.
It's possible if you've already done all of that by one way or another that just starting the launcher not via steam will resolve the problem.
I See.
And Yes I already Bound my Account in the Past in Order to use the Store with my Steam Account.
In the Meantime I did however find another Workaround for me.
As someone said the Launcher was Bugged. I went ahead and used the Horizons Launcher.
(When I start the Game over Steam it always Offers me to Start Elite Dangerous or Horizons)
It seems that whatever Bug has Afflicted the ED Launcher has not gone to the Launcher for Horizons.
So for whatever reason the Horizons Launcher Works Normal.
Well guess that Clears up the Topic as well.
So the Update Process has not yet Started. (At least not the Part which we will be affected by)
And the Youtube Picture of the Stream was not Updated to the new Stream yet.
Thanks for Helping.