First, download and run the Update Troubleshooter at the link below:
Next, you're going to run the Windows 10 update offline from the ISO file. (There are three ways to do that; from the ISO itself, from a DVD created from the ISO, or from a USB created from the ISO. All using the Media Creation Tool below.)
So, download the full Windows 10 ISO to to a folder on your computer using the Windows Media Creation Tool (Create Windows 10 installation media). After that ISO is downloaded, I've updated from all three methods above, but for the easiest, we'll just run the ISO from the folder on your computer. (If you'd prefer to do it from a DVD disk, then simply follow the instructions in the creation tool to burn the ISO image to a blank DVD.)
Once the ISO is on the computer, then unplug all USB devices, temporarily disable your antivirus (uninstall it is better), then double click on the ISO file in the folder you saved it to. Once it becomes "mounted" so you can view the internal files, double click on the "Setup.exe" file to start the update. Let it finish.
Hope this helps.
I have made four attempts to upgrade to 1803 but always fail with the Oxc1900101 error which I have yet to resolve.
I have temporarily disabled the update process in Win10 Home but have a query - each time I activate ‘update’ a laborious download begins (at 4 Mbps) - is the previous download available from my hard drive. I have searched the usual Windows files to no avail.