If you’re using Windows Update in installing Windows 10, you can implement the following:

Open the Command Prompt window by pressing Windows Key + X. Select Command Prompt (Admin) from the menu.

Stop the BITS, Cryptographic, MSI Installer and the Windows Update Services. In order to do this, Type or Copy and Paste the following commands one at a time: NOTE: Don’t forget to hit Enter after every command.

net stop wuauserv
net stop cryptSvc
net stop bits
net stop msiserver

Rename the Catroot2 and SoftwareDistribution In order to do this, Type or Copy and Paste the following commands one at a time: NOTE: Don’t forget to hit Enter after every command.

ren C:\Windows\SoftwareDistribution SoftwareDistribution.old
ren C:\Windows\System32\catroot2 Catroot2.old

Restart the BITS, Cryptographic, MSI Installer and the Windows Update Services. In order to do this, Type or Copy and Paste the following commands one at a time: NOTE: Don’t forget to hit Enter after every command.

net start wuauserv
net start cryptSvc
net start bits
net start msiserver

Type Exit in the Command Prompt then close the Command Prompt window then restart the computer. If that fails, you can try the suggestions listed in this article.

SOLUTION to this NIGHTMARE . GOT MY WINDOWS 10 updated to Version 2004 FINALLY! (and debugging recommendation for all further windows update issues) TLDR; under Windows features

If you really want you can run SetupDiag which would hunt your computer for log files and output a file called SetupDiagResults.log, but I'd suggest you try the following steps. -Went into "turn windows features on or off" type windows features in start menu (or start menu-->run -->optionalfeatures) -->from there I unchecked .Net Framework 3.5(including .NET 2.0 and 3.0) If that doesn't work try running .Net framework repair tool

OxC1900101 - 0x30018 The installation failed in the FIRST BOOT phase with an error during SYSPREP_SPECIALIZE operation

was having log file showing this. "Error: Found AdvancedInstaller Generic failure. Last Phase: Pre SysPrep Last Operation: Upgrade security Executable: SMConfigInstaller.exe Exit Code: 3222072836 Phase: 38 Mode: Install (first install) Component: WCF-GenericCommands, Culture=neutral, PublicKeyToken=31bf3856ad364e35, ProcessorArchitecture=amd64 Refer to "https://docs.microsoft.com/en-us/windows/desktop/Debug/system-error-codes" for error information. " FreeBooter mentioned this: SMConfigInstaller.exe belongs to product Microsoft® .NET Framework. If you can update .NET Framework or uninstall it and try upgrade.

Ran SetupDiag (downloaded it) as administrator and it analyzed logs files and finally one of which had a good summary under the file it generates in same folder as the exe called "SetupDiagResults.log", look for the word "Error:" ? when I didn't run as admin, it seemed to output just empty files.

debugging step (you can provide your SetupDiag log on bleepingcomputer forums under windows 10 and they may be able to assist) ..

-Went into "turn windows features on or off" type windows features in start menu (or start menu-->run -->optionalfeatures) -->from there I unchecked .Net Framework 3.5(including .NET 2.0 and 3.0) If that doesn't work try running .Net framework repair tool

I tried updating 1903/1909 for over two months. Studying winupdate logfiles(Panther logs) I found few device drivers giving errors. Uninstall RtkBluetooth driver, I do not have a bluetooth in this laptop. Also deleted SpeedFan service.

(dos console as administrator)
sc query  RtkBtFilter
sc delete RtkBtFilter
sc delete speedfan

Find registry(regedit.exe) to delete remaining references to RtkBtFilter and Speedfan services.

Remove Internet Information Services and Windows Process Activation Service in Windows features On or Off settings app. Delete c:/windows/system32/inetsrv/ folder after removing IIS service.

Install .NET 3.5 framework c:\> DISM /Online /Enable-Feature /FeatureName:NetFx3 /All, I already had NET4.8 so now have two framework releases.

Download Windows 10 Update 1909 tool from Microsoft and write image to USB memory stick. Run setup.exe from usb stick and choose an option Do not download updates while upgrading. Installation still gave a blue-screen-of-death Critical process died. After system rebooting itself it however kept update going forward and finally Windows 10 Feature 1909 was completed.

Forcing Check for windows updates in Settings app was able to download incremental patches so finally all good. My old documents and applications survived.