Some of file are missing or corrupted which is required installing the update.
Sometimes registry permission is changed or some of registry file is missing or corrupted. In case firewall does not through you o get update.
A spokesperson, reiterating that the Windows 10 free upgrade offer has ended, provided the following statement today:"Users upgrading their PC for the first time will need to enter a Windows 10 product key.
If you are trying to solve the error manually then it may causes serious damage, to prevent from it don’t solve it manually take the Regcure Pro and solve the problem automatically, just need to download.
if any registry permission or some of registry file is missing or corrupted then change permission or if missing or corrupted found then try to update registry or update registry or restore the computer for registry got found that missing or corrupted get solved.
This error is very common in windows operating system, but when this happens then it must be solve when it appears unless it will take you much bigger problem like system corruption.
Causes for getting windows update error when you try to install update:-Windows update error happens when your computer is infected by virus, malware or Trojan.
The Get Windows 10 (GWX) promotions seem to have ended.
But I've heard from several Windows users that they've been able to take advantage of the free Windows 10 update using their older Windows 7/8. Users have been able to both kick off and activate Windows 10 on machines where they've previously installed Windows 10, as well as on machines where they've never installed Windows 10 using their Windows 7/8. My ZDNet colleague Ed Bott mentioned in passing in an updated post about Windows 10 that he also was able to get Windows 10 for free after July 29 using a never-used Windows 7 Ultimate product key.
But some time it fails to update because some error happens.
Windows not valid key showing when trying to update windows operating system.
It’s very irritating when you saw update error in windows update when try to download and install update.