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api-ms-win-security-lsalookup-l1-1-0.dll is a Microsoft Windows API-set component, not a normal game DLL or Visual C++ runtime file. When api-ms-win-security-lsalookup-l1-1-0.dll is reported as missing, not found, corrupted, or unable to load, repair Windows first unless only one application is affected.
| Identification | What is known |
|---|---|
| Component | Windows API-set contract related to local security-authority lookup |
| Typical role | Provides a loader name for LSA lookup and account or SID translation functions |
| Physical file | May exist on older Windows versions, but API-set names can also be virtual aliases |
| Documented physical copies | Windows 7, Windows 8, and Windows 8.1 inventories |
| Normal location when present | Usually %windir%System32 |
| Correct source | Windows servicing and the affected application’s official installer |
| Not automatically relevant | Visual C++, DirectX, .NET, or a driver package |
What the error means
Common variants include:
- “This application failed to start because api-ms-win-security-lsalookup-l1-1-0.dll was not found.”
- “The file api-ms-win-security-lsalookup-l1-1-0.dll is missing or corrupted.”
- “Error loading api-ms-win-security-lsalookup-l1-1-0.dll. The specified module could not be found.”
- “The program can’t start because api-ms-win-security-lsalookup-l1-1-0.dll is missing from your computer.”
The wording does not prove that a physical file was deleted. Microsoft describes api-ms-win-* names as API-set contracts. They are logical names resolved by the Windows loader to an implementation supplied by the operating system. A file-search utility can therefore report that the named DLL is absent even when Windows is functioning normally.
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On Windows 7, this contract redirects to sechost.dll, which supplies the relevant security and local-account functionality. Public inventories also associate physical copies with Windows 7, Windows 8, and Windows 8.1. Their recorded versions and sizes are identification clues only, not official standalone Microsoft downloads.
First determine whether Windows or one application is at fault
Before changing files, note the exact scope:
- Only one game or program fails: repair or reinstall that application first.
- Several programs fail: suspect Windows component corruption, an incompatible operating system, malware cleanup, or antivirus quarantine.
- The failure started after an update: install all pending Windows updates and restart.
- The failure started after cleanup or antivirus action: inspect Protection History.
- The application is new: check whether it officially supports your Windows release and architecture.
- The application was downgraded or restored: its files may expect a different Windows API contract.
Also run winver:
- Press
Windows+R. - Type
winver. - Press Enter.
- Record the Windows edition and version.
To check architecture, open Settings > System > About and read System type. On 64-bit Windows, System32 contains 64-bit system components, while SysWOW64 supports many 32-bit processes through Windows file-system redirection. Do not copy files between those folders to guess which architecture is needed.
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Fix 1: Install Windows updates
Servicing updates can restore the correct Windows component state and improve compatibility with newer applications.
- Open Start > Settings.
- Select Windows Update. On some Windows 10 installations, open Update & Security > Windows Update.
- Select Check for updates.
- Install every available update.
- Restart the computer, even if Windows does not immediately require it.
- Launch the affected program again.
If the error remains, continue with the component repair commands below. Do not download a replacement DLL as the next step.
Fix 2: Repair Windows with DISM and SFC
Use an elevated Command Prompt. DISM repairs the Windows component store, and SFC uses that repaired source to replace damaged protected system files. Microsoft recommends running DISM before SFC.
- Open Start and type
Command Prompt. - Right-click Command Prompt.
- Select Run as administrator.
- Approve the User Account Control prompt.
- Run:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Wait for the operation to finish. It can remain on one percentage for several minutes.
- Then run:
sfc /scannow
- Wait until verification reaches 100 percent.
- Restart Windows and test the application.
A message stating that SFC found corrupt files and repaired them indicates that the repair changed protected system files. Test the failing program after restarting.
If DISM says that source files cannot be found:
- Connect the computer to the internet and run Windows Update again.
- If the problem persists, use a matching Windows installation source.
- Rerun DISM with the documented source syntax, replacing the placeholder with the correct source path:
DISM.exe /Online /Cleanup-Image /RestoreHealth /Source:<path> /LimitAccess
The source must match the installed Windows release and architecture. Do not use a random ISO or a different Windows version.
If SFC reports that it could not repair some files, review %windir%LogsCBSCBS.log. Microsoft documents filtering the log for [SR] entries. If Windows remains unstable, use System Restore or an in-place Windows repair installation rather than manually replacing API-set files.
Repeating SFC and DISM without knowing which step changed the system can make troubleshooting tedious. Outbyte PC Repair can show what its free scan identifies, while repair actions are handled by the full version; it is optional, and Windows servicing remains the appropriate repair path for this Microsoft component.
Fix 3: Repair or reinstall the affected application
If only one program reports the error, the application may be incomplete, damaged, or built for a Windows version that is not installed.
For a Microsoft Store-style application:
- Open Start > Settings > Apps > Installed apps.
- Find the application.
- Select its three-dot menu.
- Choose Advanced options.
- Select Repair.
- Start the application again.
For a traditional desktop program:
- Open Control Panel.
- Select Programs > Programs and Features.
- Right-click the affected program.
- Choose Repair or Change, if available.
- Follow the installer prompts.
- Restart Windows and test it.
If repair is unavailable or ineffective, uninstall the program and reinstall it from the developer’s official installer or launcher. Avoid copying the API-set name into the application directory. Reinstallation remains the definitive fix when the application’s own files are damaged.
For a game, use the launcher’s file verification feature before reinstalling the entire title. In Epic Games Launcher:
- Open Library.
- Select the three dots beside the game.
- Choose Manage.
- Select Verify.
- Wait for the scan and replacement process to finish.
- Launch the game again.
A Microsoft Q&A report shows that games can display launch failures listing several api-ms-win-* names, sometimes alongside error 0xc000007b. That code does not prove this exact API-set component is the root cause. It can also indicate broader architecture or dependency problems.
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Fix 4: Check antivirus quarantine
Windows Security may have quarantined a legitimate file, or another security product may have removed an application file.
- Open Start > Settings > Privacy & security > Windows Security.
- Select Virus & threat protection.
- Choose Protection history.
- Expand the relevant detection.
- Check the original path, file name, and publisher information.
Restore a quarantined item only when all of these are true:
- The original path is a legitimate Windows location or the application’s expected installation path.
- The file is Microsoft-signed when it is identified as a Windows component.
- The application came from its official installer.
- A current security scan finds no related threat.
Microsoft warns that allowing a real threat can put the device at risk. If the path or signature is unclear, leave the item quarantined and repair Windows with DISM and SFC. Then run a full Windows Security scan.
Fix 5: Check Windows and application compatibility
An application can require an API contract that an older Windows release does not provide. The reverse can also happen when an old application expects a different implementation.
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Check:
- Your version with
winver. - Whether Windows is 32-bit or 64-bit in Settings > System > About.
- The application’s official system requirements.
- Whether the application was designed for the current Windows release.
- Whether the error appeared after an operating-system downgrade.
Upgrade Windows when the application officially requires a newer release, or install an application version that supports the current system. Do not copy a Windows 7-era API-set file to Windows 10 or Windows 11. API-set contracts are resolved according to the Windows implementation currently installed.
Visual C++ Redistributables, DirectX, and .NET can repair other dependency errors, but there is no basis for treating them as the source of this API-set contract. Install a Microsoft runtime only when the affected application or its developer specifically requires it. The same applies to Windows Features: enabling a feature is not a general repair for an api-ms-win-* contract.
Fix 6: Investigate a related driver change
Drivers are a low-probability cause because this is a Windows API-set component, not a driver DLL. Consider a driver only when the failure began immediately after a specific driver installation and the hardware or driver vendor identifies the dependency.
To inspect drivers:
- Right-click Start.
- Select Device Manager.
- Expand the relevant device category.
- Right-click the device and choose Properties.
- Open the Driver tab.
- Use Roll Back Driver if the option is available and the problem began after an update.
- Otherwise use Update Driver and install a package from the hardware vendor.
Do not replace a system DLL as a substitute for correcting a driver installation.
Do these 3 things before closing this tab:
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Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Fix 7: Use System Restore
If the error began after a recent update, cleanup, or software installation and a restore point exists, System Restore can return system settings and components to an earlier state.
- Press
Windows+R. - Type:
rstrui.exe
- Press Enter.
- Select a restore point dated before the failure.
- Review the affected programs.
- Confirm the restore.
- Restart and test the application.
System Restore does not replace personal documents, but applications and drivers installed after the selected restore point may be affected.
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What not to do
Do not download the DLL from a random website
Unverified DLL archives can provide malware, an incorrect Windows version, a wrong architecture, or a file with an invalid signature. Even a genuine-looking copy may not match the loader contract or repair the underlying component store.
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Use Windows Update, DISM, SFC, System Restore, or the affected program’s official installer instead.
Do not copy the file into System32, SysWOW64, or a game folder
The correct location depends on Windows loader behavior, process architecture, and the installed operating system. Manual copying can create a second mismatch and hides the actual cause.
Do not run regsvr32
regsvr32 registers COM or ActiveX DLLs that expose registration entry points such as DllRegisterServer. An API-set contract or stub is not a COM component, so registration is not a repair method. A failed regsvr32 command does not diagnose this problem.
FAQ
Is this a Visual C++ Redistributable file?
No. It is associated with the Windows API-set system. Visual C++ packages may be required for other application errors, but they are not an automatic repair for this contract.
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No specific game, installer, or launcher has been established as uniquely responsible for this filename. If only one program fails, repair or reinstall that program while also checking Windows compatibility.
Should I create the missing DLL?
No. API-set names can be virtual aliases and do not always correspond to a file that should be created on disk.
Is 0xc000007b proof that this DLL is missing?
No. That error can involve multiple dependencies, architecture mismatches, or other loader failures.
What should I collect if nothing works?
Record the complete error text, application name, executable installation path, Windows version from winver, system architecture, and the change that preceded the failure. Also note whether one application or every application is affected, what DISM and SFC reported, and whether Protection History lists a quarantine event.
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