Well Microsoft continue to put out failed Operating System updates. Version 1809 has just been released (with additional bugs looking at the latest complaints) and guess what - they still haven't fixed what was causing failures previously. 1803 doesn't install
and 1809 does the EXACT same thing with EXACT same error.
Microsoft whatever you have done to the most basic of boot processes is WRONG.
If I went out and bought Windows 10 with update 1803 or 1809 on a USB or DVD and attempted to install - it wouldn't.
It does not even get past the initial boot phase to even present the option to select region and keyboard settings. Just sits there like the piece of crap software it is proving to be with the pathetic blue Microsoft logo and nothing else.
Your pre-boot environment is FLAWED from Update 1803 onwards. Whatever change you made from 1709 to 1803 in the pre-boot (Supposed "SAFE" OS phase) is flawed.
So if 1803 didn't install for you - don't even waste your precious time with the failure that is 1809.