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Get the fix to the <strong>Fatal: INT18: Boot failure</strong> boot error message affecting <strong>Windows XP, Windows Vista, Windows 7, Windows 8, Windows 8.1, </strong>, and <strong>Windows 10</strong>.
<h2>About the "<strong>Fatal: INT18: Boot failure</strong>" error</h2>
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<h3>Description and Symptoms</h3>
The error messages, alerts, warnings, and symptoms below are tied to this error.
<h4>Symptom 1: Fatal: INT18: Boot failure error screen on startup</h4>
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, <a href="http://neosmart.net/wiki/mbr-boot-process/">as part of the boot process</a> 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, 8.1, and Windows 10:

<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/INT18-boot-failure.png"><img class="alignnone wp-image-3732 size-full" style="border-top: 26px solid black; border-left: 20px solid black;" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/INT18-boot-failure.png" alt="INT18 boot failure error screen" width="720" height="400" /></a>
<pre>FATAL: INT 18: BOOT FAILURE</pre>
<h3>Causes of this Error</h3>
This error has been known to occur as a result of one of the following causes:
<h4>Cause 1: There are no active partitions available</h4>
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.
<h4>Cause 2: Active partition bootsector is not valid</h4>
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.
<h2>Fixing "Fatal: INT18: Boot failure" on Windows</h2>
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<h3>Fix #1: Mark partition as active via Easy Recovery Essentials</h3>
<div class="content dynamic_content_max_width"><span class="message_body">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.</span></div>
[easyre error="FATAL: INT 18: BOOT FAILURE" bootscreen="xp-vista-7-8" guaranteed="true"]
<h3>Fix #2: Use Windows’ built-in Automatic Repair</h3>
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:
<ol>
 	<li>Boot from Windows install disc</li>
 	<li>Click <strong>Next</strong> in the setup page after selecting proper language, time and keyboard input</li>
 	<li>Click <strong>Repair your computer</strong> and select <strong>Troubleshoot</strong></li>
 	<li>Click on <strong>Advanced options</strong></li>
 	<li>Select <strong>Automatic Repair</strong> and select your operating system.</li>
</ol>
Here is an example screenshot of System Recovery Options Menu.

<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/Sysres1.png"><img class="alignnone wp-image-3738 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/Sysres1.png" alt="System Recovery Options Menu" width="800" height="600" /></a>
<h3>Fix #3: Mark partition as active using Diskpart</h3>
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:
<ol>
 	<li>Boot from the Windows install disc</li>
 	<li>Click on <strong>Repair your computer</strong> after after selecting proper language, time and keyboard input</li>
 	<li>Select the Windows installation drive, which is usually <code>C:\</code>, and click <strong>Next</strong></li>
 	<li>Choose Command Prompt when the System Recovery Options box appears</li>
 	<li>Write the following command and press <kbd>Enter</kbd> afterwards:
<pre>diskpart</pre>
</li>
 	<li>Then, write
<pre>list volume</pre>
to get the list of all available partitions, and press <kbd>Enter</kbd>.</li>
 	<li>Then, write
<pre>select volume X</pre>
to select the volume you want to mark as active, and press <kbd>Enter</kbd></li>
 	<li>Then, write
<pre>active</pre>
to mark the currently selected volume as active, and press <kbd>Enter</kbd></li>
</ol>
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:

[caption id="attachment_3737" align="alignnone" width="800"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/VirtualBox_Win7_clean_27_04_2016_05_45_20.png"><img class="wp-image-3737 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/VirtualBox_Win7_clean_27_04_2016_05_45_20.png" alt="Diskpart utility results screen" width="800" height="600" /></a> Diskpart utility results screen[/caption]
<h3>Fix #4: Mark partition as active using Windows Disk Management</h3>
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:
<ol>
 	<li><span id="post_message_629057" class="mediatut">Type <b>diskmgmt.msc </b>into the start menu, and press <kbd>Enter</kbd>.</span><span id="post_message_629057" class="mediatut"></span><img class="alignnone size-large wp-image-3750" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/Diskmgmt_Win7_menu-1024x576.png" alt="Diskmgmt_Win7_menu" width="980" height="551" /></li>
 	<li>Right click on the partition you want to mark as active, and select <strong>Mark partition as Active</strong>.<img class="alignnone size-large wp-image-3751" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/Diskmgmt_Win7_screen-1024x576.png" alt="Diskmgmt_Win7_screen" width="980" height="551" /></li>
</ol>
<h2>More Information</h2>
<h3>Linked Entries</h3>
<ul>
 	<li><a href="https://neosmart.net/wiki/set-partition-as-active/">How to set partition as active</a></li>
</ul>
[partial name="partial_moreinfo" versions="xp,vista,7,8,8.1,10"]