Cannot get KB4586781 to install successfully

For a few weeks my laptop (Windows 10 Professional V.2004) has failed to successfully apply an update KB4586781. After the install it errors

Your device is missing important security and quality fixes.

Some update files are missing or have problems. We'll try to download the update again later. Error code: (0x8007000d)

No matter how many times I've tried it always fails like this.

So today I decided to apply 20H2 update, hoping that would install and then KB4586781 would become redundant (or would install OK). But that failed We couldn't install this update, but you can try again (0x8007000d).

I'd speculate this is a consequence of it not being up to date before applying 20H2. So chicken and egg.

It only seems to be the KB4586781 update that fails, other updates have gone through.

FWIW at the beginning of October I replaced the HDD with a Samsung EVO 1TB drive, using Samsung migration software to clone the disc. Worked first time after installing the SSD.

[At each of the following stages I’ve rebooted the PC before re-running the update]

Run the Reset_Reregister_Windows_Update_Components batch file to no avail.

I've run Update Troubleshooter twice, again to no avail.

Run
dism.exe /online /cleanup-image /scanhealth
dism.exe /online /cleanup-image /restorehealth
again to no avail.

Have downloaded the KB4586781 update and updated manually, that failed.

Deleted all from C:\Windows\SoftwareDistribution\Download\
Run manual update again. Failed

sfc /scannow Errors found, Can't attach the CBS.log file as at 45MB it's too large.
dism.exe /online /cleanup-image /restorehealth OK
chkdsk /scan OK

This is the command window result

Microsoft Windows [Version 10.0.19041.388](c) 2020 Microsoft Corporation. All rights reserved.C:\Windows\system32>sfc /scannowBeginning system scan. This process will take some time.
Beginning verification phase of system scan.
Verification 100% complete.
Windows Resource Protection found corrupt files and successfully repaired them.
For online repairs, details are included in the CBS log file located atwindir\Logs\CBS\CBS.log. For example C:\Windows\Logs\CBS\CBS.log. For offlinerepairs, details are included in the log file provided by the /OFFLOGFILE flag.C:\Windows\system32>dism /online /cleanup-image /restorehealthDeployment Image Servicing and Management toolVersion: 10.0.19041.329Image Version: 10.0.19041.388
[===========================84.9%================= ][===========================85.4%================= ][===========================86.4%================== ][===========================87.5%================== ][===========================88.7%=================== ][===========================89.7%==================== ][===========================90.8%==================== ][===========================91.8%===================== ][==========================100.0%==========================]
The restore operation completed successfully.
The operation completed successfully.
C:\Windows\system32>chkdsk /scan
The type of the file system is NTFS.
Stage 1: Examining basic file system structure ...
702464 file records processed.
File verification completed.
Phase duration (File record verification): 7.18 seconds.
12490 large file records processed.
Phase duration (Orphan file record recovery): 0.00 milliseconds.
0 bad file records processed.
Phase duration (Bad file record checking): 0.62 milliseconds.
Stage 2: Examining file name linkage ...
30417 reparse records processed.
838442 index entries processed.
Index verification completed.
Phase duration (Index verification): 12.66 seconds.
0 unindexed files scanned.
Phase duration (Orphan reconnection): 1.85 seconds.
0 unindexed files recovered to lost and found.
Phase duration (Orphan recovery to lost and found): 0.60 milliseconds.
30417 reparse records processed.
Phase duration (Reparse point and Object ID verification): 100.62 milliseconds.
Stage 3: Examining security descriptors ...
Security descriptor verification completed.
Phase duration (Security descriptor verification): 113.95 milliseconds.
67990 data files processed.
Phase duration (Data attribute verification): 0.88 milliseconds.
CHKDSK is verifying Usn Journal...
39436648 USN bytes processed.
Usn Journal verification completed.
Phase duration (USN journal verification): 290.26 milliseconds.
Windows has scanned the file system and found no problems.
No further action is required.
976249556 KB total disk space.
315212520 KB in 295723 files.
193124 KB in 67991 indexes.
0 KB in bad sectors.
849776 KB in use by the system.
65536 KB occupied by the log file.
659994136 KB available on disk.
4096 bytes in each allocation unit.
244062389 total allocation units on disk.
164998534 allocation units available on disk.
Total duration: 22.23 seconds (22231 ms).
C:\Windows\system32>

Run manual update again. Failed.

Clean boot. Run manual update again. Failed.

Removed MalwareBytes (using Revo)

Disabled Samsung Magician. Not sure why it wasn't picked up in the preparation for clean boot.

Run manual update again. Failed.

Rerun Update Troubleshooter twice, 1^st found a couple of errors, including security descriptor(?)

Run manual update again. Failed.

Any more thoughts?

At the moment I can't install 20H2 to see what it's like before letting it near my main, desktop, PC.

Apologies for delay, the last week has been manic, and next week looks much the same. I'll follow up on the suggestions when time permits. Thank you for them.

For both my PCs Windows has offered me the update, I haven't explicitly sought it.

One of the reasons for keeping my PCs up to date is that a number of people contact me for PC help (several this past week alone) and will often have a PC that has the latest Windows. Apart from the current CU issue I have never had a significant problem with installing the latest Windows so I prefer to keep up to date. My choice, if I get a major problem I'd revert. And of course I take a full Reflect backup beforehand.

Thanks, my bad. Now done for both desktop and laptop (it's the laptop that's fails to update)

As said in the OP my laptop won't update to 2004, I've tried it. Possibly because the CU update mentioned is failing. As dalchina said in post #2 an in-place upgrade repair install may be necessary.

My desktop is ready to go but I've held back, deliberately.