sfc /scannow WILL NOT function

(1) "My pc is x64-based on everything you suggested"

OK, you've got an x64-based computer, & a 64-bit version of Windows is installed on it. It can run both 32-bit & 64-bit programs. Your folders sound right. That 1909 Installation USB is the 64-bit version. All is well.

(2) Regarding Windows system image backup...

(a) Yes, use the one at "START, Settings, Update & Security, Backup, Go to backup & Restore (Win 7), Create a system image". I don't know how the one inside File History works. If you've turned that on, see whether you can have it not make images. Even turn it off altogether.

(b) Did you try to include D: partition in the image? It's possible HP did something to it that makes it incompatible. And they never should have put a letter on it, if they don't want folk to use it. Simply don't select it when the app asks. Take only EFI, C:, & Recovery, which are preselected. (Eventually, we want to nuke D: partition anyway.)

(c) Because we are doing the clean install into a dual boot, it isn't critical to make the system image. We're not wiping the current partitions. Only EFI will have a file within it (the BCD store) adjusted to offer a choice of which installation to boot. The 1909 installation otherwise goes wholly into that 150 GB space we created, & its own internal recovery environment (Shift+Restart) will be in a folder on C: instead of in a partition.

You could backup just the BCD store this way. Make a folder in C: named "BU". Then, at an Administrator Command prompt, enter "BCDEdit  /Export  C:\BU\BCD_Backup". If necessary, it can be restored with **"BCDEdit  /Import  C:\BU\BCD_Backup"**in a recovery environment. But don't do an /Import just for fun.

(3) D: partition is for getting Win 8.1 back with all the HP add-ons. If the clean install goes well into a dual boot & you like the outcome -- we will repeat the clean install, this time wiping all the partitions away. D: partition will be replaced by periodic Windows system images of your own -- the first of which will be made while in the dual boot from 1909. That way, if the 2nd clean install goes bad, we'll be able to recover the 1st one.

(4) "Yes, sandisk device is there"

That's it, then. (If two were there, you'd choose the one that said "UEFI".)

(a) Select it to boot to the 1909 Installation USB drive. (You've been there before.)

(b) Click "Install Now".

(c) Click "Custom Install".

(d) When asked where to install, select the 150 GB unallocated space, & click "Next".

28 minutes later (plus whatever it takes to answer Cortana) you'll have your dual boot. Then there'll be a screen each reboot asking which to boot into. Likely they'll both say "Windows 10". The 2nd one likely is 1909. We can change those names, but I don't think we'll be keeping both for long.

I'll be in tears, if something goes horribly wrong -- but don't let it stop you telling me.

2)  "I don't understand what you've been saying about 32-bit." I think I had asked about why somethings like cmd will say windows32 instead of 64 but I guess that's just what it does. Also I have folders for program files and program files (x86) and that some downloads/installs/software give choices for 32 or 64. Because I had older programs from old computers that were moved to this one I thought I might need to have both 32 and 64 available though I suppose I should just chuck them and move on. My pc is x64-based on everything you suggested.

3a)  Windows system image backup failed - Error window "Windows cannot access the specified device, path, or file. You may not have the appropriate permissions to access them." We couldn't back up your data. To find out more look up error code 0x800704C7. I looked up the error and tried this

https://answers.microsoft.com/en-us/windows/forum/all/windows-backup-wont-start-error-code-0x800704c7/795724d2-b686-4616-be6a-8e5b5b4a8d0b

which uses "backup files (windows 7)" option but it didn't work either.

I honestly use my external drives for all my work and keep copies backuped on them anyway. So I don't know if backup image does more. Programs are the only things I don't have on my externals I think.

3b) I downloaded drivers and moved them to an external drive.

3c) Yes, there are back ups files and folders

on my externals.

4)   "What is your D:partition?" HP site https://support.hp.com/us-en/document/c01512976 says - Recovery (D): is a special partition on the hard drive used to restore the system in the event of problem. Recovery (D:) drive can be seen in Windows Explorer as a usable drive, you should not attempt to store files in it. Storing files can on the Recovery (D:) drive can cause the system recovery process to fail.

No, I  never use it in anyway.

 Inside of D: there is a recovery partition

• WARNING -

This area of your hard drive (or partition) contains files used to perform a system recovery.

Do not delete or alter any of these files.

Any change to this partition coul revent a system recovery in the future.

Again I don't touch it.

So it's a leave it alone partition.

5. I shrunk C: and there is 150.1 GB unallocated.

6c)  "Is the USB drive shown? " Yes, sandisk device is there. I didn't enter into it in case it started something I wasn't suppose to do. All did as you asked.

.

(1) OK. Now, I only did this once, but it was quick & easy. I can only hope it will go as well for you. Cortana began asking questions after 17 minutes. Nine minutes after answering, the entire installation was over. I still can't believe it was only 28 minutes to establish the dual-boot. There were at least 3 automatic reboots in the process.

(a) Tell Cortana your Microsoft account password when asked. I believe that facilitates activation. Mine was fully activated afterward. Also, I did not have to reestablish connections to Mail, OneDrive or the Store. Those were all there by the end of the process same as before, same as in the other installation. Nevertheless: You should backup important OneDrive files to external media, in case it goes not so well for you.

(b) Tell Cortana your WiFi password (written on the router), & you will have WiFi when its over.

(c) All of my Dell/Intel/Realtek driver versions were retained, but my notes say Action Center had a notice to reboot to complete the install of Dell HD Audio. I did that, & the message was gone. Also, it says I had to reinstall my Dell Touchpad driver.

(d) Reliability History (ask Search) will show stuff still goes on afterward. It may be a day/so before everything is fully updated.

(e) It was clean. Finally, all of McAfee & all else that was a Dell add-on was gone (except the drivers).

(f) I did lose one specialized keyboard key (a super WiFi toggle), but I don't miss it.

(g) It doesn't mess with BIOS or other firmware. Those are unaffected.

(h) Afterwards, Windows Update had stuff -- go click for it.

(I) If unhappy, the dual boot is easily undone. If happy, it probably is best to redo the clean install, this time onto a totally wiped HDD. That way, you'll have just the right number of partitions & just where they belong.

(2) I don't understand what you've been saying about 32-bit.

(a) What does it say for System Type in MSInfo32 (ask Search) -- is it "x64-based PC"?

(b) Plug in your 1909 Installation USB drive. Note the letter it gets, & use that letter (instead of E:) for the following command at an Administrator Command Prompt...

DISM  /Get-WimInfo  /WimFile:E:\Sources\Install.esd  /Index:1

Here's what I get...

Microsoft Windows [Version 10.0.18363.836]

(c) 2019 Microsoft Corporation. All rights reserved.

C:\WINDOWS\system32>DISM  /Get-WimInfo  /WimFile:E:\Sources\Install.esd  /Index:1

Deployment Image Servicing and Management tool

Version: 10.0.18362.1

Details for image : E:\Sources\Install.esd

Index : 1

Name : Windows 10 Home

Description : Windows 10 Home

Size : 14,513,453,277 bytes

WIM Bootable : No

Architecture : x64                                      <<< Does yours say x64?

Hal : <undefined>

Version : 10.0.18362

ServicePack Build : 418

ServicePack Level : 0

Edition : Core

Installation : Client

ProductType : WinNT

ProductSuite : Terminal Server

System Root : WINDOWS

Directories : 21327

Files : 92708

Created : 10/6/2019 - 11:07:10 PM

Modified : 11/18/2019 - 11:41:45 PM

Languages :

        en-US (Default)

The operation completed successfully.

(3)

(a) Try another Windows system image backup. I hope it works.

(b) Download important drivers from your site just in case...

https://support.hp.com/us-en/drivers/selfservice/hp-pavilion-21-h000-touchsmart-all-in-one-desktop-pc-series/6528604/model/6529764

HP Pavilion 21-h013w TouchSmart All-in-One Desktop PC

The site looks tough to figure with so many different drivers in some of the categories. I say take nothing that doesn't already show up in "right-click START, Device Manager". Let me know, if one of them is puzzling.

(c) Backup important files & downloads onto external media, including OneDrive files, just in case of catastrophe.

(4) What is your D: partition? It's unusual for a factory reinstall partition (to get back to Win 8.1) to have a letter, I think. Do you ever write to that partition? Does an HP app use it?

(5) Shrink C: by 150 GB in preparation for the dual boot.

(a) Right-click START, & select Disk Management (DM).

(b) Right-click C: in DM, & select Shrink Volume.

(c) Enter 153600 into the Amount to Shrink box, & click the Shrink button.

     That will be 150 GB (150 * 1024).

You should now see that much unallocated space between C: & D:. Later, you will install into that space to achieve the dual boot. I don't think you'll be asked to reboot, but I'd do it anyway.

(6) Practice a boot to your 1909 Installation USB drive through the BIOS boot menu.

(a) Plug it in, then reboot.

(b) Immediately press ESC repeatedly for the Startup Menu.

(c) Press F9 at that screen for the "Boot Device Options" screen.

     I think it then shows you boot options --  is the USB drive shown?

(d) Then select it to boot to the 1909 Installation USB drive.

That's just a dry run to see whether you can get there. If so, back out, you're all set.

OK, practice that, & answer the questions. Then I'll write-up how to do the dual boot.