Get the fix to the Fatal: INT18: Boot failure boot error message affecting Windows XP, Windows Vista, Windows 7, Windows 8, and Windows 8.1.

About the “Fatal: INT18: Boot failure” error

The following information on this error has been compiled by NeoSmart Technologies, based on the information gathered and reported by our global network of engineers, developers, and technicians or partner organizations.

Description and Symptoms

The error messages, alerts, warnings, and symptoms below are tied to this error.

Symptom 1: Fatal: INT18: Boot failure error screen on startup

When an operating system is installed on the hard drive, the installer marks the partition that contains the boot files for that OS as active. Every time a computer with that OS is turned on, as part of the boot process the BIOS loads and starts the first sector on the bootable drive. The first sector on that disk (typically called an MBR or Master Boot Record) contains code that checks the partition table for a partition that is marked as active, and loads the first sector of that partition (the boot sector). However, if there are no active partitions available, then the loading process halts, and “Fatal: INT18: Boot Failure” error is displayed.

Here is a screenshot example of a Fatal: INT18: Boot failure error screen on Windows XP, Vista, 7, 8, and 8.1:

INT18 boot failure error screen

FATAL: INT 18: BOOT FAILURE

Causes of this Error

This error has been known to occur as a result of one of the following causes:

Cause 1: There are no active partitions available

If MBR can’t find an active partition on the current disk to boot from, then the system loading process halts. This is usually caused by errors made while configuring the partitions manually.

Cause 2: Active partition bootsector is not valid

If MBR tries to pass execution on to an active partition that does not have a valid, executable bootsector, then this error may also appear. The bootsector can be sometimes damaged by disk write errors, boot sector infecting viruses, or power outages.

Fixing “Fatal: INT18: Boot failure” on Windows

Windows Setup CD/DVD Required!
Some of the solutions below require the use of the Microsoft Windows setup CD or DVD. If your PC did not come with a Windows installation disc or if you no longer have your Windows setup media, you can use Easy Recovery Essentials for Windows instead. EasyRE will automatically find and fix many problems, and can also be used to solve this problem with the directions below.

Fix #1: Mark partition as active via Easy Recovery Essentials

Easy Recovery Essentials’ one-click automated system repair corrects issues caused by incorrect active partition configuration. If EasyRE does not find an active partition, it will correct the problem by identifying the single, correct boot partition and marking it as active. This is done automatically as part of the automated repair process, and requires no manual action or user intervention.

Easy Recovery Essentials is guaranteed to fix the “FATAL: INT 18: BOOT FAILURE” error automatically using its built-in Automated Repair option. EasyRE is currently available for Windows XP, Vista, 7 and 8 and can be downloaded and created on any PC.

  1. Download Easy Recovery Essentials. Make sure to note your Windows version (XP, Vista, 7 or 8) before you download EasyRE. This guide can help you identify what version of Windows you have installed.
  2. Burn the image. Follow these instructions on how to burn the bootable ISO image very carefully, as making a bootable CD can be tricky! Alternatively, these instructions explain how to create a bootable EasyRE recovery USB stick/drive.
  3. Boot up your PC from the Easy Recovery Essentials CD or USB you created.
  4. Once EasyRE is running, choose the “Automated Repair” option and click Continue.
    EasyRE Home

    Choose “Automated Repair” in Easy Recovery Essentials

  5. After EasyRE scans your computer’s drives, identify and select the drive letter for your Windows installation from the list, and then click on the Automated Repair button to begin.
    EasyRE displays a list of found Windows operating systems

    Choose the drive associated with the Windows installation you’re trying to repair.

  6. Easy Recovery Essentials will start analyzing the selected drive for problems. EasyRE will test for and attempt to automatically correct errors with the disk, partition, bootsector, filesystem, bootloader, and registry. No intervention is required, as EasyRE’s repair is fully automated:
    EasyRE: Automated Repair

    Easy Recovery Essentials searches for errors and makes corrections to the selected Windows installation.

  7. Once the process is complete, EasyRE will report its findings. Click on the Restart button to reboot your PC and test the changes.
  8. The “FATAL: INT 18: BOOT FAILURE” error should now be fixed as your PC begins to load:
    EasyRE: Automated Repair

    Windows, booting up successfully.

You can download Easy Recovery Essentials from here.

Fix #2: Use Windows’ built-in Automatic Repair

The Windows Automatic Repair can be used to mark the disk partition as active to fix this error. Here are the steps to access the Automatic Repair from an install disc:

  1. Boot from Windows install disc
  2. Click Next in the setup page after selecting proper language, time and keyboard input
  3. Click Repair your computer and select Troubleshoot
  4. Click on Advanced options
  5. Select Automatic Repair and select your operating system.

Here is an example screenshot of System Recovery Options Menu.

System Recovery Options Menu

Fix #3: Mark partition as active using Diskpart

The built-in Diskpart Windows utility can also be used to mark a partition as active. Note that the marked partition must contain the Windows bootloader for Windows to load correctly.

Here are the steps to run Diskpart and change the disk’s status:

  1. Boot from the Windows install disc
  2. Click on Repair your computer after after selecting proper language, time and keyboard input
  3. Select the Windows installation drive, which is usually C:\, and click Next
  4. Choose Command Prompt when the System Recovery Options box appears
  5. Write the following command and press Enter afterwards:
    diskpart
  6. Then, write
    list volume

    to get the list of all available partitions, and press Enter.

  7. Then, write
    select volume X

    to select the volume you want to mark as active, and press Enter

  8. Then, write
    active

    to mark the currently selected volume as active, and press Enter

Here is an example screenshot of what the PC’s console output should look like after the volume is properly marked as active with Diskpart:

Diskpart utility results screen

Diskpart utility results screen

Fix #4: Mark partition as active using Windows Disk Management

If the user has a second copy of Windows installed on another drive, he can boot into it to his first disk’s partition as active. Alternatively, if he has another working PC available, he may connect his hard drive to that PC to mark the drive’s partition as active from there.

Here are the steps to run Windows Disk Management and mark a partition as active:

  1. Type diskmgmt.msc into the start menu, and press Enter.Diskmgmt_Win7_menu
  2. Right click on the partition you want to mark as active, and select Mark partition as Active.Diskmgmt_Win7_screen

More Information

Linked Entries

Support Links

Applicable Systems

This Windows-related knowledgebase article applies to the following operating systems:

  • Windows XP (all editions)
  • Windows Vista (all editions)
  • Windows 7 (all editions)
  • Windows 8 (all editions)
  • Windows 8.1 (all editions)

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