how to fix Feature update to Windows 10, version 2004 failed - 0xc19001e1

So it's been ten months, and my PC (an ASUS ZenBook Duo purchased in May of 2020) STILL has not been able to install the 2004 update. Despite the fact that the failed update somehow disabled the second built-in display for which I'd paid the extra $2,000 (I spent weeks with ASUS tech support trying to get that fixed, and they ultimately blamed Microsoft and left me adrift), I'd given up fighting with it after six months -- but now Windows is giving me warnings that support for my version of Win10 is being discontinued, and it's back to attempting to update itself (and promptly BSODing at 48% install) daily. I am spending as much time waiting on my computer to restart as I am actually working on it.

I have tried all the previous suggestions in this thread that apply to my machine. I have over 1TB of disk space free. I have cleared system files and cleaned up previous failed installs. I have no virus or malware issues. I'm running a native install of Windows 10 Pro (this machine was literally less than a month old when the update was released!). Since Microsoft clearly hasn't implemented a fix, does anyone have ANY other suggestions to try?

Thanks for posting, I too am a 'tired old geezer' and have worked in IT for decades. I'm not running a dual boot system either, just Windows 10.
I gave it another try for about 2 hours, beyond fed up. I tried the commands at the command prompt and none of them seem to work (yes in CMD prompt as admin) They all return errors, 'not recognized as an internal or external command, operable program or batch file'
I give up.... again :-)

This answer may not apply to you but it fixed my problem and I would like others in my situation to see it.

N.B.

1. I dual boot windows and Linux. My PC boots using GRUB.
2. I had already tried stripping my hardware down to the basics plus all the stuff mentioned/linked to here.
3. This will prevent Linux from booting until you use something like "Boot-Repair-Disk" to rebuild GRUB so have it ready before you do any of this to rebuild your dual boot after the 2004 update has installed or in case fixing the MBR causes other problems.

I got the update to work by fixing the Windows master boot record (MBR).

Method:

Boot from a Windows 10 CD and, after the locale options, select “Repair your computer” (bottom left of the screen) and then “Troubleshoot” and then "Command Prompt". Once at the command prompt, type the following:

bootrec.exe /fixmbr

bootrec.exe /scanos

bootrec.exe /rebuildbcd

exit

I have seen other people say you need to do a "bootrec.exe /fixboot" as well but, in my case, that came back with a permissions error and omitting it made no difference to my outcome.

After a reboot your PC will go straight into Windows.

Either wait for Windows to upgrade itself or download the update assistant from the Microsoft website and do it that way.

If you like me are having a problem with a HP ZBook device and/or is running a HP Dock with Thunderbolt 3, then I found a solution that worked for me: HP Support page

For me it was both the Synaptics/Conexant audio driver for the built-in device, AND Synaptics/Conexant audio driver for the HP Dock (named HP Dock audio in device manager).

If you are running some other kind of Thunderbolt dock, it might also be worth to check that the audio driver for that dock is newish (mine was from 2019), otherwise uninstall driver for it (make sure to uninstall driver files), unplug dock, reboot and then try running Windows Update again.

And as I wrote on the linked page:

And if someone at HP is reading this - shame on you for not providing a fix for this!

And if someone at Microsoft is reading this - why haven't you provided a workaround for this or published information on how to do it. And publicly shamed HP+Synaptics for this mess. This problem has been with us for about a year since it also faulted the 2004 feature update (already insider builds).