Try updating to 1809 using Media Creation tool and if it fails let us know.
The fastest way to get the upgrade is through Media creation tool or ISO file.
Please download Media Creation Tool from the link below and select Upgrade this PC at the first screen.
https://go.microsoft.com/fwlink/?LinkId=691209
All steps, including upgrading using ISO file and Media creation tool, are covered here:
https://www.yourwindowsguide.com/2018/10/update...
Disclaimer:
This is a non-Microsoft website which would provide accurate and safe information. Watch out for ads on the site which are frequently classified as a PUP (Potentially Unwanted Products). There is no need to buy paid products to fix your computers as they do more harm than good sometimes.