[Solved] 2 issues during upgrade of preinstalled win8 64 bit to 8.1 (Dell Inspiron)

I ordered a Dell pc (Feb 2014) which came preinstalled with win8_64 and after getting all the updates I was offered the upgrade to win8.1. When I clicked on the upgrade in the Microsoft store I was confronted with the following screen which told me I have to retry with administrator account. I checked my fresh created account and I was administrator. Luckily I found the answer here:

• Navigate to Control Panel > Uninstall a program > View installed updates (located on the left pane) > Uninstall the Microsoft Update KB2871389

After doing this you can go back to Microsoft Store and your download will start ..

Next I ran into the issue that The installation stalled at 63-64%, to get it moving again just disconnect from the internet as was mentioned here. You can go back to your upgrade to Win8.1 tile and your installation will continue and soon be progressing beyond 63%