Fix Windows Server Boot Failure After Windows Update

This guide explains how to recover a Windows Server system that fails to boot after a Windows Update. The process uses Windows Recovery Environment and DISM to revert or remove problematic updates. This tutorial applies to Windows Server 2019 but is similar for other versions.

Step 1 — Obtain Windows Installation Media

Download the Windows Server ISO matching your OS version.
Search for: "Windows Server 2019 Evaluation"
Download the ISO from Microsoft's official website.
Create bootable media:
- Write ISO to USB
- OR mount ISO via iDRAC Virtual Media
Boot the server from the installation media.

Note: If the server entered a recovery loop after failed boots, it may automatically show the recovery screen without external media.

Step 2 — Enter Windows Recovery Environment

Boot to installation media
Select Next
Click Repair your computer
Select:
- Troubleshoot
- Command Prompt

Step 3 — Identify Windows Drive Letter

In recovery mode, the system drive may not be C:. You must locate the Windows installation manually.

dir C:
dir D:
dir E:

Look for a folder named Windows. Whichever drive contains it is your OS drive.

Example: Windows found on D:\

Step 4 — Revert Pending Windows Updates

Run DISM to cancel unfinished update operations:

dism /image:D:\ /cleanup-image /revertpendingactions

Replace D:\ with your actual Windows drive.

This process may take several minutes if updates were pending.

When complete:

Close Command