To update, last night restarting my computer did not work to update the launcher, but somehow signing out and signing back in seemed to get it to update after a few minutes, and I was finally able to play.
However, the same issue struck tonight, and I did not restart my computer. I did close and reopen the launcher, and log out and log back in, and neither had any effect. I did your method Deighzed, and reinstalled the old launcher (it just works :P). I didn’t get an error message, it just reinstalled bnet in the same folder and started updating WoW, and after a brief Updating: 0% scare on the beta tab while trying to switch to the old launcher, the update went through.
I’m still supremely unimpressed with the cluttered mess that is the beta launcher, and equally irritated that I was unable to play WoW because of these errors. I tried to submit a ticket to make sure they are aware of this issue, but even though I had everything filled out and a dxdiag file uploaded the submit button was grayed out so I’ve given up on that front. I just hope they are somehow aware of this issue and get it fixed. And I hope they also give us an option to keep the old launcher, though I know we won’t be so lucky.
Thanks for your help and I hope you have a good day. Take care and good luck to anyone else with this issue.