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Get the fix to the <strong>0xc0000001: A required device isn't connected or can't be accessed</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>0xc0000001</strong>" error</h2>
[kbintro]
<h3>Description and Symptoms</h3>
The error messages, alerts, warnings, and symptoms below are tied to this error.
<h4>Symptom 1: 0xc0000001 error screen on startup</h4>
The 0xc0000001 error can be caused by a wide variety of causes, with the most common one being system file corruption, or damaged memory. Alternatively, this error can also be caused by a missing or damaged SAM(Security Account Manager) system file.

<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/0xc0000001-boot-error1.png"><img class="alignnone wp-image-4464 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/0xc0000001-boot-error1.png" alt="0xc0000001 boot error screen" width="687" height="536" /></a>
<pre>Windows failed to start. A recent hardware or software change might be the cause. To fix the problem:

1. Insert your Windows installation disc and restart your computer. 
2. Choose your language settings, and then click "Next." 
3. Click "Repair your computer."

If you do not have this disc, contact your system administrator or computer manufacturer for assistance.

Status: 0xc0000001

Info: A required device isn't connected or can't be accessed.</pre>
On newer system, another error screen is displayed instead:

<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/Error-Code-0xc0000001.png"><img class="alignnone wp-image-4465 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/Error-Code-0xc0000001.png" alt="0xc0000001 boot error screen" width="840" height="547" /></a>
<pre>Windows Recovery Environment

Your PC couldn't start properly

A required device isn't connected or can't be accessed.

Error code: 0xc0000001

You'll need to use the recovery tool on your installation media. If you don't have any installation media like disc or USB devices, contact your system administrator or PC manufacturer.

Press Enter to try again
Press F8 for alternate boot options</pre>
Note that the exact error message may vary from case to case, but the error code for this error is always "0xc0000001".

Alternatively, you may also see an error message right after Windows loads:

<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/0xc0000001.png"><img class="alignnone wp-image-4466 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/0xc0000001.png" alt="0xc0000001 boot error screen" width="800" height="600" /></a>
<pre>Security Accounts Manager initialization failed because of the following error: A device attached to the system is not functioning. Error Status: 0xc0000001. Please click OK to shut down this system and reboot into Safe Mode, check event log for more detailed information.</pre>
<h3>Causes of this Error</h3>
This error has been known to occur as a result of one or more of the following:
<h4>Cause 1: SAM file is damaged</h4>
The SAM(Security Accounts Manager) file stores the user credentials data and is essential to Windows booting process. If that file is missing or corrupt, then the boot process is halted.
<h4>Cause 2: System files are damaged</h4>
Sometimes, this error may occur when the key boot-related system files become damaged because of disk write error, power outages or virus attacks.
<h4>Cause 3: File system integrity compromised</h4>
Alternatively, this error appears when the whole file system gets damaged on a grander scale for the same reasons.
<h4>Cause 4: RAM is damaged</h4>
In the worst case scenario, the PC's memory could be permanently damaged.
<h2>Fixing "0xc000000e" on Windows</h2>
[setupcd]
<h3>Fix #1: Use Easy Recovery Essentials</h3>
[easyre error="0xc0000001" bootscreen="xp-vista-7-8-10"]
<h3>Fix #2: Copy the SAM File from the Repair Folder</h3>
If you're able to login into Windows, copy the SAM file from <code>C:\WINDOWS\repair to C:\WINDOWS\system32\config</code>. To do that, boot from a Windows Install CD, open a command prompt, and enter:
<pre>copy C:\Windows\Repair\Sam C:\Windows\System32\Config</pre>
If asked whether you want to overwrite the original file, reply "Y"(Yes).
<p class="warning">This will remove all login credentials your Windows copy has, including username and password and revert back to the original username that was added when you installed Windows.</p>

[caption id="attachment_4468" align="alignnone" width="800"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/copysam.png"><img class="wp-image-4468 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/copysam.png" alt="SAM file restored from a backup" width="800" height="600" /></a> SAM file restored from a backup[/caption]
<h3>Fix #3: Run chkdsk</h3>
If the hard drive has its file integrity compromised, it is possible to use built-in Windows CHKDSK utility to scan the disk and fix the file system errors.

Here are the steps to run CHKDSK:
<ol>
 	<li>Boot from your Windows install disc</li>
 	<li>Click on <strong>Repair your co</strong><strong>mputer</strong> 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>chkdsk C: /f</pre>
Replace C: with the letter of the driver where Windows is installed.</li>
</ol>
Here is an example of what the PC's console output should look like once the chkdsk.exe is complete:

[caption id="attachment_3697" align="alignnone" width="800"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/VirtualBox_Win7_clean_21_04_2016_03_58_48.png"><img class="wp-image-3697 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2016/04/VirtualBox_Win7_clean_21_04_2016_03_58_48.png" alt="Chkdsk utility results screen" width="800" height="600" /></a> Chkdsk utility results screen[/caption]
<h3>Fix #4: Check RAM</h3>
Check if you recently added any new RAM modules. Users have reported that a new RAM module was the actual cause for this boot error. Replace the RAM modules to see if they are causing this error to appear.
<h3>Fix #5: Run sfc /scannow</h3>
On Windows Vista and Windows 7, it is possible to use the built-in Windows SFC(system file checker) tool to automatically scan a computer's system files and repair them if necessary.

Here are the steps to run SFC:
<ol>
 	<li>Boot from your Windows install disc</li>
 	<li>Click on <strong>Repair your co</strong><strong>mputer</strong> 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>sfc /scannow /offbootdir=D:\ /offwindir=D:\Windows\</pre>
Replace D: with the letter of the driver where Windows is installed, and D:\Windows with the Windows folder location.</li>
</ol>
Here is an example of what the PC's console output should look like once the sfc.exe scan is complete and missing files are successfully restored:

[caption id="attachment_4233" align="alignnone" width="800"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/sfc_result.png"><img class="wp-image-4233 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/sfc_result.png" alt="System files restored by the SFC utility" width="800" height="600" /></a> System files restored by the SFC utility[/caption]
<h3>Fix #6: Check the HDD</h3>
If the error is caused by damaged hard disk cables, try any of the following tips to fix the error:
<ul>
 	<li>Try a different port for the SATA/IDE cables</li>
 	<li>If you have more than 1 HDD, leave only the HDD with Windows installed and test multiple SATA/IDE ports and cables</li>
</ul>
The "A disk read error occurred" error can appear if:
<ul>
 	<li>The SATA/IDE cables are damaged</li>
 	<li>The SATA/IDE ports of your hard disks are damaged</li>
</ul>
If the HDD cables and ports are not damaged, the issue can also be from the hard disk itself.

To test if your hard disk is failing or it's already failed, use <a href="https://neosmart.net/EasyRE/">Easy Recovery Essentials' Automated Repair</a>. Automated Repair process will report any issues found with your hard disk or RAM memory:

[partial name="partial_easyre_hardware_testing"]
<h3>Fix #7: Use Windows Startup Settings</h3>
<ol>
 	<li>Restart your computer</li>
 	<li>Press <kbd>SHIFT</kbd> + <kbd>F8</kbd> when booting to open the Recovery screen</li>
 	<li>Select the <strong>Advanced repair options</strong></li>
 	<li>Go to <strong>Troubleshoot</strong> and then <strong>Advanced Options</strong></li>
 	<li>Select <strong>Windows Startup Settings</strong></li>
 	<li>Click <strong>Restart</strong></li>
</ol>
[caption id="attachment_4467" align="alignnone" width="800"]<a href="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/Startup.png"><img class="wp-image-4467 size-full" src="https://neosmart.net/blog/wp-content/uploads/sites/5/2013/08/Startup.png" alt="Startup Settings screen" width="800" height="600" /></a> Startup Settings screen[/caption]
<h2>More Information</h2>
<h3>Linked Entries</h3>
<ul>
 	<li><a href="https://neosmart.net/wiki/sfc/">sfc</a></li>
 	<li><a href="https://neosmart.net/wiki/chkdsk/">chkdsk</a></li>
 	<li><a href="https://neosmart.net/wiki/advanced-boot-options-menu/#Windows_8">Advanced Boot Options menu on Windows 8</a></li>
</ul>
[partial name="partial_moreinfo" versions="xp,vista,7,8,10"]