My Windows 10 Version 20H2 will not install the update 0x80004005.

Been trying to fix this all day, it's ridiculous. I've tried everything and been speaking to Microsoft support for over 3 hours now as I couldn't find a method and still no fix

I have two identical laptops.  One updated and the other did not.  I have used all of the fixes suggested but no luck after months of trying.  Everywhere I turn and try is a deadend.  I have spent hours trying to resolve the problem but I can't put my finger on the actual problem since so much is not seen during an update.  Now I have about 10 updates in the pending and the fail.  I'm not sure even a reinstall would fix the problem.  It's just interesting  that Microsoft has not issued something since there are so many people with this issue.

I have researched and fixed my own with the two-step process.

Step 1:  Find out if your "Windows" system drive is GPT or not via Check if Disk is MBR or GPT in Windows | Tutorials (tenforums.com)

 -- if your Windows drive is MBR, you will need to convert it to GPT.  Google is your friend for this.

Step 2:  If all drives look GPT and your still not getting the 'upgrade assistant' (https://www.microsoft.com/software-download/windows10) to let you start 20H2 update, than you are like me, where the GPT 'table' (?) gets hosed up and you have to boot into 'safe mode' command line to run "sfc" with special parameters.  There's a thread on that: How to Fix a No Bootable Device Error on Windows 10 (helpdeskgeek.com)  Look for the section "Scan for Corrupt System Files Using SFC" and pay attention to the drive letters.  In this case there is SOMETHING that re-assigned drive letters to UEFI and you need to fix that with the steps they show for using the option /offwindir and /offbootdir to set YOUR correct drive letter.

No re-install required if this is really the root cause.

Good luck.

Thanks man I'm going to do this as well. What do i need tondo the NAS backups and so. I dont want to lose everything andrreinstall all my programs. I have a lot of programs work related. Not even thinking about all my games. 

well my friend, 

reinstalling stuff is a dead cert with my method, can't be avoided!

all i know is that i have external back ups of all my music, photos, vids etc, to a WD NAS                                                     

easy to put back in place after fresh install.

I'm not sure about programs, i just reinstalled from their respective websites, tried desperately to remember the logins then dragged n dropped the content from the external drive to the appropriate folder in the new comp drive.

would suggest you do a full back up of all your content to an external hard drive before removing anything.

as for your game data.....you'd need to reach out to someone else who knows , i don't have a clue!

I'm onto Motorhead and tequilla now, you're lucky i can still type.....

good luck!

Thanks. I will give it another try.