This morning I unexpectedly installed the new Windows 10 Fall Creators Update Version 1709. I was trying to update my Windows Defender Definitions and it wouldn't, so I went to the Windows Settings page and tried the Updates request there. Next thing I knew it was working on the 1709 update! After a while it advised me it had problems and to check error 0x80070020. I did and it said it could be a conflict with my other virus protection (Malwarebytes). Then I noticed it was just after 7:00 AM when I have Malwarebytes scheduled to do its daily morning scan, and that was the problem. When Malwarebytes was done I restarted Windows and again went to the Settings page and got the 1709 update underway with no problems. It took around 45 minutes or less and I had no further problems.
Warning: When you try to use the new Defender Antivirus the first time and run a Quick Scan, instead of my usual 2 to 3 minutes, it automatically runs a first FULL scan which took my computer about 13 minutes. The next Quick scan was back to just a couple of minutes.
Good luck!
