“ext-ms-win-advapi32-psm-app-l1-1-0.dll” was not found
You may see one of these messages when starting an older application or game:
The program can’t start because ext-ms-win-advapi32-psm-app-l1-1-0.dll is missing from your computer.
This application failed to start because ext-ms-win-advapi32-psm-app-l1-1-0.dll was not found.
Other variants include “Error loading,” “The code execution cannot proceed,” or “not designed to run on Windows or it contains an error.”
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This filename is legitimate, but it is not a normal application DLL that you should download and copy into a folder. It is a Microsoft Windows API-set contract name. Windows can use that name as a loader alias and route it to the correct implementation for the installed Windows version. A physical file with this exact name does not have to exist on every computer. Microsoft explains Windows API sets here.
Which fix applies to you
Use this order:
- The error affects several programs: repair Windows components with Windows Update, DISM, and SFC.
- Only one program or game fails: repair or reinstall that program from its original installer or launcher.
- The problem began after antivirus cleanup: inspect Windows Security protection history before restoring anything.
- The program is old or unsupported: update Windows and check the application’s supported Windows versions.
- A dependency scanner reports this name as unresolved: do not assume a missing physical DLL. API-set imports can be displayed misleadingly.
- Every application is failing: treat the problem as Windows instability and continue to System Restore or a Windows repair reinstall.
Do not begin by searching for a standalone download of this filename.
1. Install Windows updates and restart
An outdated or damaged Windows installation may not resolve an API-set contract correctly for a particular application.
Windows 11
- Open Start > Settings.
- Select Windows Update.
- Click Check for updates.
- Install all available updates.
- Restart the computer, even if Windows does not immediately require it.
- Launch the affected program again.
Windows 10
- Open Start > Settings.
- Select Update & Security.
- Open Windows Update.
- Click Check for updates.
- Install the available updates and restart.
If the error started immediately after an update, record the update date and continue with the repair commands below. Do not remove system files manually.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errors2. Repair Windows with DISM and SFC
Microsoft recommends running DISM before System File Checker. DISM repairs the Windows component store, while SFC uses that repaired store to check and replace protected system files. Microsoft’s repair instructions contain the same sequence.
- Open Start.
- Type
Command Prompt. - Right-click Command Prompt.
- Select Run as administrator.
- Approve the User Account Control prompt.
- Run this command:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Wait for DISM to finish. It may use Windows Update as its repair source.
- Then run:
sfc /scannow
- Wait until verification reaches 100 percent.
- Restart Windows and test the application.
Do not close the Command Prompt while either scan is running. SFC may report that it found and repaired corrupted files, found no integrity violations, or could not repair some files.
If DISM cannot obtain repair files through Windows Update, use a genuine matching Windows repair source:
DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:C:RepairSourceWindows /LimitAccess
Replace C:RepairSourceWindows with the path to a valid repair source matching your Windows edition and version. Do not use a random downloaded folder.
Running DISM and SFC repeatedly without knowing which component changed makes troubleshooting difficult. Outbyte PC Repair can scan for system issues and show what needs attention; its repair actions are handled by the full version. It is optional, and Windows’ built-in commands remain the appropriate first repair step.
3. Repair or reinstall the affected application
If only one program produces the error, the application installation or its compatibility with Windows is more likely than a universal missing DLL.
First look for a repair option:
- Open Start > Settings.
- Select Apps.
- Choose Apps & features on Windows 10, or Installed apps on Windows 11.
- Find the affected application.
- Open its menu or select Advanced options.
- Choose Repair, if available.
- Test the program.
If repair does not help, uninstall and reinstall it:
- Close the program and its launcher.
- Open the application’s official installer source or launcher.
- Uninstall the program through Settings > Apps or the launcher.
- Restart Windows.
- Install the current version using the original vendor installer.
- Start the program normally.
For a game, use the launcher’s file repair feature where available. This may be named Verify integrity, Verify files, or Repair installation. Do not copy ext-ms-win-advapi32-psm-app-l1-1-0.dll into the game folder. Reinstalling the affected application remains the definitive fix when its own files or installer are damaged.
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4. Check antivirus quarantine safely
Security software may quarantine a genuine file after detecting suspicious behavior in an application. It may also correctly block a modified or infected program.
In Windows Security:
- Open Start > Settings.
- Select Privacy & security on Windows 11, or Update & Security on Windows 10.
- Open Windows Security.
- Select Virus & threat protection.
- Click Protection history.
- Review entries related to the affected program.
- Note the original file path, detection name, publisher, and action taken.
Only restore or allow a file when you have verified its original location and digital signature and are confident the application installer is trustworthy. Microsoft warns that allowing a file can reintroduce malware risk. See Microsoft’s Protection History guidance.
If the quarantined item belongs to the application, reinstall the program from its official source instead of restoring an uncertain file. Run a current security scan if the quarantine entry is unexpected.
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5. Check Windows and application architecture
A 32-bit application and a 64-bit application can have different dependencies. An error from a dependency inspection tool does not necessarily mean that a physical DLL is absent.
Check Windows architecture:
- Open Start > Settings > System > About.
- Read System type.
- Record whether Windows is 64-bit or 32-bit.
Then check the application’s requirements and architecture from its original vendor documentation or installer. Do not download a “32-bit” or “64-bit” copy of this filename based only on the error text.
If a dependency tool reports the API-set contract as unresolved but the program launches normally, the report may reflect how the tool understands API-set aliases rather than a real Windows failure. If the program does not launch, use the application’s own installer and Windows repair steps instead.
6. Do not install Visual C++ or DirectX automatically
Visual C++ Redistributables and DirectX are often suggested for every DLL error, but they do not repair this API-set contract.
Microsoft’s packages normally use names such as:
vc_redist.x86.exevc_redist.x64.exevc_redist.arm64.exe
They provide C and C++ runtime files such as msvcp*.dll and vcruntime*.dll. Install a Visual C++ package only when the complete error identifies one of those runtime files or the application’s vendor specifically requires it. Use Microsoft’s latest supported Visual C++ Redistributable downloads.
The same rule applies to DirectX, .NET, and graphics drivers. Install them only when the application’s requirements or its complete error message points to them. They are not a general replacement for ext-ms-win-advapi32-psm-app-l1-1-0.dll.
7. Update drivers only when the evidence points there
A graphics or device driver is not the normal explanation for this API-set contract. Check drivers when the application also crashes with display, audio, input, or hardware-specific errors.
To inspect drivers:
- Right-click Start.
- Select Device Manager.
- Expand the relevant category, such as Display adapters.
- Right-click the device.
- Select Update driver.
- Choose Search automatically for drivers.
- Restart if Windows installs an update.
For a graphics driver, use the hardware manufacturer’s official support page when Windows Update does not provide the required release. Outbyte Driver Updater can scan for outdated drivers and identify the relevant package; its driver installation is handled by the full version. It is optional and is not a substitute for repairing the affected application.
8. Use Windows’ built-in recovery options
If DISM and SFC find no problem but many applications fail, Windows itself may be unstable.
Windows 11 repair reinstall
Windows 11 includes a supported option to reinstall the current version while preserving apps, files, and settings:
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- Open Start > Settings.
- Select System > Recovery.
- Find Fix problems using Windows Update.
- Select Reinstall now.
- Follow the prompts and keep the computer connected to power.
Microsoft documents this process in its Windows repair reinstall instructions.
System Restore
If the error began after a recent software installation or system change:
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One-click scans. No signup required.
- Open Start.
- Search for
Create a restore point. - Open the result.
- Select System Restore.
- Choose a restore point from before the problem began.
- Review the affected programs and complete the wizard.
System Restore rolls back system files, registry settings, and installed programs without intentionally changing personal files. Back up important work before recovery.
If every application continues to fail, back up your data and consider an in-place repair installation, Reset this PC, or a full Windows reinstall.
Why regsvr32 is not the fix
Do not run:
regsvr32 ext-ms-win-advapi32-psm-app-l1-1-0.dll
regsvr32 calls a DLL’s DllRegisterServer entry point. That is intended for registerable COM or ActiveX components, not for Windows API-set contracts or ordinary runtime dependencies. It cannot create a missing API-set mapping and may produce an entry-point or registration error. Microsoft documents regsvr32 here.
Do not copy a DLL from another Windows installation either. The result can be a version, servicing, signature, or architecture mismatch.
FAQ
Is this filename legitimate?
Yes. It follows Microsoft’s API-set naming scheme and appears in Windows API-set references. Legitimate does not mean it should be downloaded as a standalone file.
Should the file be in System32 or SysWOW64?
Not necessarily. API-set names can be virtual loader aliases and do not have to correspond to a physical file with that exact name.
Is it a Visual C++ or DirectX file?
No verified evidence identifies it as a Visual C++ or DirectX redistributable file. Repair those packages only when the complete error specifically names their runtime files.
Can I download it from a DLL website?
No. An unofficial copy may contain malware, be the wrong architecture, be incompatible with your Windows build, or fail to address the real application or Windows problem.
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Outbyte PC Repair FREERepair Windows errors before they cause bigger problemsFix Now →Outbyte Driver Updater FREEScan for outdated or missing drivers - takes under a minuteDriver Scan →What information should I collect if the error remains?
Record the Windows version and build, application name and version, 32-bit or 64-bit architecture, complete error text, and whether the problem began after an update, cleanup, antivirus action, or application change. That information separates a Windows repair problem from an application installation problem.
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