Software & Apps Windows How to Fix Ntdll.dll Errors A troubleshooting guide for Ntdll.dll errors by Tim Fisher General Manager, VP, Lifewire.com Tim Fisher has 30+ years' professional technology support experience. He writes troubleshooting content and is the General Manager of Lifewire. our editorial process Facebook Twitter LinkedIn Tim Fisher Updated on November 10, 2019 Windows The Ultimate Laptop Buying Guide Tweet Share Email The causes of ntdll.dll error messages can vary greatly. However, most ntdll.dll errors result from a corrupt or damaged version of the ntdll DLL file itself, corrupt hardware drivers, or issues between Windows and other programs. Ntdll.dll errors can sometimes mean that a piece of hardware in your computer is malfunctioning, but this is rare. There are many different ways that ntdll.dll errors may be displayed on your computer. They can be caused by a number of different things which result in many different error messages, but these are some of the most common: STOP: 0xC0000221 unknown hard error C:\Winnt\System32\Ntdll.dllSTOP: C0000221 unknown hard error \SystemRoot\System32\ntdll.dllAppName: [PROGRAM NAME] ModName: ntdll.dll[PROGRAM NAME] caused a fault in module NTDLL.DLL at [ANY ADDRESS]Crash caused in ntdll.dll!NTDLL.DLL Error!Unhandled exception at [ANY ADDRESS] (NTDLL.DLL) Ntdll.dll error messages might appear before or after a program is used, while a program is running, when Windows is started or shut down, or even during a Windows installation. Ntdll.dll error messages can apply to nearly any Windows-based software program, driver, or plugin on any of Microsoft's operating systems from Windows NT up through Windows 10, Windows 8, Windows 7, Windows Vista, and Windows XP. How to Fix Ntdll.dll Errors Restart your computer. The ntdll.dll error you're receiving could be due to a one-time, temporary issue and a simple reboot may resolve the problem completely. Reinstall the program if the ntdll.dll error only displays when you use a specific program. If the software program has any updates or service packs available, install them, too. The software's programmers may have identified an issue with the program that caused the ntdll.dll error and then issued a patch for it. Third-party software programs that have been installed on your computer are almost always the cause of ntdll.dll errors. The remainder of these troubleshooting steps resolves ntdll.dll issues only rarely. Check the Windows service pack level you're running and then check this page to see if there's a more recent service pack available for installation. Some issues that caused ntdll.dll errors have been corrected in these service packs from Microsoft. The easiest way to update your Windows computer with the newest service pack and other patches is to use Windows Update. Follow our guide on How to Check for and Install Windows Updates if you need help. Selectively disable Internet Explorer add-ons. If your ntdll.dll error is displaying when you start, run, or close Internet Explorer, an add-on may be causing the problem. Disabling each add-on, one by one, will determine which add-on is the culprit (if any). As a workaround, assuming the ntdll.dll error really is Internet Explorer related, install and use a competing browser like Firefox. Rename the NLSPATH system variable. If your Windows system does not have this environment variable, skip this step. This is a troubleshooting step for this issue only. Be sure to set this path back to its original name if this does not resolve the ntdll.dll issue. Disable Data Execution Prevention for Explorer.exe. As in the previous step, this is for troubleshooting the ntdll.dll issue only. If this doesn't resolve the problem, return the Data Execution Prevention settings to their previous settings. Disable UAC. This is a workaround for some causes of ntdll.dll issues but could serve as a permanent solution if not using User Account Control is something you're comfortable with on your computer. Update drivers for any hardware in your computer where updated drivers are available. Outdated drivers sometimes cause ntdll.dll errors. Test your memory for damage. If you're receiving ntdll.dll messages, one possible cause could be a bad memory module in your system. Testing your memory will either identify a problem or clear your RAM of any responsibility. Replace your memory if it fails any of your tests. Ntdll.dll errors could occur if you have an Iomega Zip drive on the same IDE cable as the hard drive inside your computer. If so, move the Zip drive to a dedicated IDE controller. Replace the IDE cable connecting the hard drive to the motherboard. If this cable is damaged or malfunctioning, one symptom could be the ntdll.dll error you're seeing. Repair your installation of Windows. If individual software reinstallations fail to resolve the problem, a repair installation of Windows will replace the ntdll.dll file. Perform a clean installation of Windows. A clean installation will completely remove Windows from your PC and install it again from scratch. I don't recommend this option unless you've exhausted all previous troubleshooting ideas and you're comfortable that the ntdll.dll error is not caused by a single program (Step #2). If a single program or plugin is causing the ntdll.dll error, reinstalling Windows and then reinstalling all of the same software may lead you right back to the same ntdll.dll error. If everything else has failed, including the clean installation from the last step, you could be dealing with a hardware issue with your hard drive. However, this is extremely rare. If so, replace the hard drive and then perform a new installation of Windows. Need More Help? If you don't want to fix this ntdll.dll problem yourself, see How Do I Get My Computer Fixed? for a full list of your support options, plus help with everything along the way like figuring out repair costs, getting your files off, choosing a repair service, and a whole lot more.