Windows NT boot problem: Kernel file is missing from the disk

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Article ID: 155892 - View products that this article applies to.
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When you start Microsoft Windows NT you receive the following error message:
A kernel file is missing from the disk. Insert a system disk and restart the system.

The message is displayed before the boot options from the Boot.ini are shown.


The file NTLDR is missing from the active system partition or the allocation for \Ntldr's $DATA attribute has become so fragmented that the whole $DATA attribute is not in the base FRS (file record segment).


After the Power On Self Test (POST), the Master Boot Record (MBR) reads the partition table and jumps to the boot record.

The code that generates the error is in the boot record. The error is generated if the NTLDR file cannot be found or if the $DATA attribute cannot be found.

Windows NT File System (NTFS) views each file or directory as a set of file attributes. Elements such as the file's name, its security information, and its data are all file attributes. Each attribute is identified by an attribute type code and, optionally, an attribute name.


When you experience this problem, follow these steps, and then obtain the Bcupdate.exe program:
  1. Boot Microsoft Windows NT from floppy (using the NTLDR on the floppy disk).
  2. Move the NTLDR file to a different physical location on disk (ren ntldr ntldr.sav, copy ntldr.sav ntldr).
  3. Use an NTFS defrag utility to unfragment NTLDR.
  4. Ensure the correct partition is marked active using either NT Disk administrator, or Boot to DOS and use FDISK.EXE to ensure the correct system partition is marked for boot.
Obtain the Bcupdate.exe program, which updates the boot code of the NTFS bootsector. For information on obtaining the individual software update, contact Microsoft Product Support Services. For a complete list of Microsoft Product Support Services phone numbers and information on support costs, please go to the following address on the World Wide Web:;EN-US;CNTACTMS
Once you have obtained the software update create a Windows NT startup floppy disk and boot Windows NT using this disk. - Extract Bcupdate.exe and NTLDR from the software update.

- Run Bcupdate.exe C: /F.

- Other command line parameters supported:

/q - Quiet mode (must include /y).
/y - Don't confirm.
/f - Force update of in use volume.
/t - Only test for old boot code.


Microsoft has confirmed this to be a problem in Microsoft Windows NT 3.5x and 4.0.


Article ID: 155892 - Last Review: November 1, 2006 - Revision: 3.3
  • Microsoft Windows NT Workstation 3.51
  • Microsoft Windows NT Workstation 4.0 Developer Edition
  • Microsoft Windows NT Server 3.51
  • Microsoft Windows NT Server 4.0 Standard Edition
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