Windows 10 Anniversary update stuck at 91%

Updating all out 5 family PC's to the latest Win10 anniversary update was easy, .... except the one that kept stalling at 91%. In fact it was the latest addition to our PC park, a HP Envy.

After some googling, searching for reasons for this, I applied the following procedure what cured it. Now updating went smooth even on this device. I could not not identify the exact cause but anyway, it helped.

1. Image the current installation.
   Just to be on the save side. Basically when the update blocks you can power off/on the device and it reverts to the previous installation, ... but you never know.
2. Run the Windows Update Troubleshooter: Win+troubleshoot, "Fix problems with windows update"
   This did not find anything but it might with your installation.
3. Nvidia graphics driver: uninstall.
4. Avira Anti-Virus software: uninstall, including its launcher
5. Disable Windows Defender
6. Disable Windows Firewall
7. Disable all non-Microsoft Services: Win+msconfig, Services, "hide all MS Services", "Disable all"
8. Disable all startup Apps: Taskmanager, Startup, disable all

For this to complete several reboots were required.

Then start the windows 10 Anniversary update.

After the update completes, revert the actions above in the opposite order.

.... May the luck be with you!