Upgrade to 2025 from 2022 error 0xC1900101 - 0x40021

Question

Trying to upgrade server from 2022 to 2025 and am getting this error. Nothing in the event logs. it is a Hyper-V VM but no problems upgrading other VMs. Any help would be greatly appreciated. Thanks

Answer 1

Hi Bill,

This error is occurring during the second boot phase (SYSPREP/re-specialization), which indicates the VM is failing while attempting to reconfigure system settings post-upgrade. Since other VMs are upgrading successfully, the issue is likely related to this particular VM’s configuration or environment.

Here are some recommended steps to diagnose and resolve the issue:

1. Reset Windows Update Components

Corrupted update components can trigger SYSPREP failures. Open PowerShell as Administrator and run the following commands:

net stop wuauserv

net stop cryptSvc

net stop bits

net stop msiserver

net start wuauserv

net start cryptSvc

net start bits

net start msiserver

2. Check the disk and repair any system-level issues:

Open Powershell with Admin mode:

chkdsk /f /r

You may be prompted to reboot. After that, run:

DISM /Online /Cleanup-Image /RestoreHealth

sfc /scannow

3. If the system still fails during re-specialization, you can try running SYSPREP manually:

C:\Windows\System32\Sysprep\sysprep.exe /generalize /oobe /reboot

Please make sure to back up the VM before performing this step.

4. In some cases, disabling certain integration services helps complete the upgrade:

Shut down the VM.

Open Hyper-V Manager → Right-click the VM → Settings → Integration Services.

Uncheck:

"Operating system shutdown"

"Time synchronization"

Restart the upgrade process.

Should you have any questions, feel free to let me know.

Answer 2

Finally got around to this. Did not do a sysprep, but looked as the logs in $Windows.~BT\Sources\Panther and $Windows.~BT\Sources\Rollback and found 1 service that was erroring out with a bad memory issue. It was an old service from 2008 that did work on 2022. Uninstalled it and Veola all good.