Others are reporting this issue too, its probably best you file a bug report then roll back until it is fixed:
https://answers.microsoft.com/en-us/windows/for...
send me the short link so I can vote on it and bring it to the attention of the Windows engineers.
https://windows10.help/blogs/entry/54-how-to-su...
Open Start > Settings > Update & security > Recovery > under Go back to my previous version of Windows 10, click Get started.
or
Press Control + Alt + Delete
Click Sign out
At the Sign In screen, hold down the shift key on your keyboard while clicking the Power button on the screen
Continue to hold down the shift key while clicking Restart
Continue to hold down the shift key until the Advanced Recovery Options menu appears
Click Troubleshoot
Click Advanced options
Click Go back to the previous version of Windows
Windows Update might attempt to upgrade to Windows 10 1809 again. See instructions how to block it:
https://www.groovypost.com/howto/block-windows-...
Information in the above link is sourced from a trusted Microsoft MVP blog.