Just got this from the mod
What is the date of your backup?
That is important because the Update package has been modified at least once since it's original release on April 8.
If your backup is Apr 8 or before, you do have a greater chance of success.
If you choose to restore to your backup, I would suggest you try this before attempting the update.
From an Administrator Command Prompt window run these DISM commands
- DISM.exe /Online /Cleanup-image /Scanhealth
- DISM.exe /Online /Cleanup-image /Restorehealth
Reboot
If one of the commands fails, that would demonstrate a problem existed before the Update.
If the commands show success, your machine should be ready to apply the update.
I would recommend the manual method of obtaining the package from the Download Center and installing it that way.
Looking at the dates you must be the unluckiest person in the world