api-ms-win-crt-locale-l1-1-0.dll Is Missing: Safe Windows Fixes

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The program can’t start because api-ms-win-crt-locale-l1-1-0.dll is missing from your computer. Try reinstalling the program to fix this problem.

If api-ms-win-crt-locale-l1-1-0.dll is missing, Windows or the affected application cannot resolve part of the Microsoft Universal C Runtime. When api-ms-win-crt-locale-l1-1-0.dll was not found, the safest solution is to repair the matching Windows or Visual C++ runtime instead of downloading a replacement DLL.

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Which fix applies to you

Use the first description that matches what you are seeing:

• If several programs fail with similar api-ms-win-crt-*.dll errors, install Windows updates, then run DISM and SFC.
• If only one program or game fails, repair or reinstall that application from its official installer.
• If the program is 32-bit, install the x86 Visual C++ Redistributable even when Windows itself is 64-bit.
• If the error appeared after an interrupted installation or game update, verify the application files before changing Windows components.
• If you use Windows 7, Windows 8, Windows 8.1, or an embedded edition, install the applicable Microsoft Universal CRT update.
• If the error started after antivirus activity, check Protection History and reinstall the affected program if its local runtime files were removed.
• If the error mentions a module rather than only this DLL, the actual missing file may be a dependency beside it.
• Do not copy this DLL from a random download site, and do not run regsvr32 on it.

The fixes below are ordered from the safest and most likely solution to the more specialized cases.

What api-ms-win-crt-locale-l1-1-0.dll actually is

api-ms-win-crt-locale-l1-1-0.dll is a Microsoft Universal C Runtime API-set component. It exposes locale-related C-runtime functions, including functions associated with locale selection and locale information.

That does not make it a Windows language pack. It is not a game-specific library, DirectX component, .NET assembly, Visual Basic runtime, or device driver. Native Windows applications built with modern Microsoft C++ toolsets can depend on the Universal C Runtime, which is why unrelated software may display the same error.

Microsoft describes API-set names as contracts or aliases used by the Windows loader. Depending on the Windows build, an API-set name may be represented by a physical forwarder DLL or handled as a virtual alias. It is therefore not guaranteed that every Windows installation will contain a literal file with this exact name. See Microsoft’s Windows API sets documentation.

The implementation behind the API-set is primarily associated with ucrtbase.dll. The API-set name identifies the interface that an application expects, not necessarily the physical binary that performs every operation.

If a copy exists inside an application’s installation directory, that copy may have been installed by the program itself as an application-local runtime. If the application depends on Windows’ centrally deployed UCRT, Windows services that component through the operating system. Microsoft’s Universal CRT deployment documentation explains both deployment models.

What the error messages mean

Windows can show several loader messages for the same underlying problem:

The program can't start because api-ms-win-crt-locale-l1-1-0.dll is missing from your computer. Try reinstalling the program to fix this problem.

This application has failed to start because api-ms-win-crt-locale-l1-1-0.dll was not found. Re-installing the application may fix this problem.

The code execution cannot proceed because api-ms-win-crt-locale-l1-1-0.dll was not found. Reinstalling the program may fix this problem.

Error loading api-ms-win-crt-locale-l1-1-0.dll. The specified module could not be found.

api-ms-win-crt-locale-l1-1-0.dll is either not designed to run on Windows or it contains an error.

These messages do not always prove that this particular DLL is the only damaged or missing file. In particular, “The specified module could not be found” can mean that a dependency required by the named component is missing.

The application architecture also matters. A 32-bit program requires x86 runtime components, while a 64-bit program requires x64 components. On 64-bit Windows, both runtime families can be installed at the same time.

Fix 1: Install Windows updates first

On Windows 10 and Windows 11, the UCRT is part of Windows and is normally serviced through Windows Update. Start with this step before reinstalling individual runtime packages.

1. Open Start.
2. Select Settings.
3. Open Windows Update.
4. Select Check for updates.
5. Install every available update.
6. Restart the computer, even if Windows does not insist on an immediate restart.
7. Launch the affected program again.

Microsoft’s current instructions are available under Install Windows Updates.

If the program launches after the restart, the missing component was probably supplied by an incomplete or pending Windows update. If Windows Update reports that the system is current but the error remains, continue with the component repair steps below.

Do not assume that installing the latest Visual C++ package always repairs a corrupted Windows 10 or Windows 11 UCRT. The centrally deployed UCRT follows the Windows operating system version, so Windows servicing remains important.

Fix 2: Repair Windows with DISM and SFC

Use this fix when several programs fail, Windows Update reports errors, the problem began after an interrupted update, or the application still reports missing UCRT files after updating.

DISM repairs the Windows component store. SFC then checks protected system files against that repaired component store. Microsoft recommends running DISM before SFC.

Run DISM

1. Open Start.
2. Type Command Prompt.
3. Right-click Command Prompt.
4. Select Run as administrator.
5. Approve the User Account Control prompt.
6. Enter this command:

DISM /Online /Cleanup-Image /RestoreHealth

1. Wait for the operation to finish.
2. Leave the administrator Command Prompt open.

A successful run ends with a completion message. The process can remain at one percentage for a while, so do not close the window merely because the progress appears unchanged.

Run System File Checker

After DISM finishes, enter:

sfc /scannow

Wait until verification reaches 100 percent. Then restart Windows and test the affected application.

A useful result is a message stating that Windows Resource Protection found and repaired corrupted files. If SFC reports that it found no integrity violations, Windows’ protected files were not detected as damaged, but that does not prove that the application installation or an application-local runtime is healthy.

If DISM cannot find repair files, use a matching Windows installation source and follow Microsoft’s Repair a Windows image guidance. A command using a suitable source has this general form:

DISM /Online /Cleanup-Image /RestoreHealth /Source:wim:X:\sources\install.wim:<matching-index> /LimitAccess

Replace X: and the image index with values from installation media that closely matches the installed Windows edition and build. Do not guess the index or use an unrelated Windows image.

Outbyte PC Repair can reduce the manual work of repeatedly running repair checks: its free scan shows what it detects, while repair actions are performed by the full version, so Windows Update, DISM, and SFC remain the appropriate built-in path when the component store itself is damaged.

If DISM and SFC complete successfully but one application still fails, move to application repair and the matching Visual C++ package rather than repeatedly running the same commands.

Fix 3: Repair or reinstall the affected application

When only one program reports this error, the program’s own installation is a strong possibility. The application may have an incomplete app-local runtime, missing companion files, or a failed update.

Repair through Windows Settings

On Windows 11:

1. Open Start.
2. Select Settings.
3. Open Apps.
4. Select Installed apps.
5. Find the affected program.
6. Select the three-dot menu beside it.
7. Choose Advanced options, if available.
8. Select Repair.
9. Launch the application again.

On Windows 10, the equivalent path is generally Settings > Apps > Apps & features. Select the program and use Advanced options > Repair when the program provides that option.

Repair normally keeps the application’s user data while replacing or checking program files. If there is no Repair button, use the program’s own installer or Control Panel.

Repair through Control Panel

1. Open Start.
2. Type Control Panel.
3. Open Programs.
4. Select Programs and Features.
5. Select the affected application.
6. Choose Repair or Change, if offered.
7. Complete the installer.
8. Restart the application.

If repair fails, uninstall and reinstall the program using the publisher’s official installer. Reinstalling is especially important when the application originally bundled its own copy of the UCRT.

For a game, use the launcher’s file-verification feature before reinstalling the entire game. In Steam, the path is:

Library > right-click the game > Properties > Installed Files > Verify integrity of game files

A successful verification normally reports that the files were checked and either confirms them or downloads replacements. If the launcher repeatedly redownloads the same files, the installation, storage device, security software, or update process may be interfering.

Fix 4: Install or repair the matching Visual C++ Redistributable

The file belongs to the Microsoft Visual C++ runtime family, and applications commonly install or depend on the Visual C++ Redistributable in addition to the Windows UCRT.

Use Microsoft’s Latest Supported Visual C++ Redistributable Downloads page. The current v14 package links are:

• x86 Visual C++ Redistributable
• x64 Visual C++ Redistributable
• ARM64 Visual C++ Redistributable

Choose the correct architecture

• Install x86 for a 32-bit application.
• Install x64 for a 64-bit application.
• Install ARM64 for an ARM64 application.
• On 64-bit Windows, install both x86 and x64 when you use programs of both types.

A 64-bit Windows installation does not make a 32-bit application an x64 application. The architecture of the failing executable determines which redistributable it needs.

To identify an application’s architecture, check its documentation or installer requirements. For a program already installed, its publisher may identify the architecture in the download name or system requirements. If you use both 32-bit and 64-bit software, keeping both corresponding redistributables installed is normal.

Install or repair the package

1. Download the matching package from Microsoft’s official page.
2. Close the affected application.
3. Run the downloaded installer.
4. Accept the license terms.
5. Choose Install if the package is absent.
6. Choose Repair if the installer detects an existing installation and offers repair.
7. Restart Windows.
8. Launch the affected program.

If the installer says that a newer version is already installed, use its Repair option if available. Do not uninstall every Visual C++ Redistributable on the computer. Different applications may depend on different runtime generations, and older redistributables can remain installed side by side.

If repairing Visual C++ changes nothing on Windows 10 or Windows 11, return to Windows Update and DISM/SFC. The redistributable installer does not replace every part of the centrally serviced Windows UCRT.

Fix 5: Follow the legacy Windows UCRT path

Windows 7, Windows 8, Windows 8.1, and older embedded Windows installations may need a separate Universal CRT update. This is particularly relevant when a newer application is installed on an older operating system.

Microsoft identifies KB2999226 as the initial Universal CRT release and KB3118401 as a later update containing fixes. Use Microsoft’s Update for Universal C Runtime in Windows documentation to determine the applicable package.

The legacy process is:

1. Install all available updates through Windows Update.
2. Restart the computer.
3. Confirm that Windows 7 has Service Pack 1.
4. Confirm that Windows 8.1 has the required servicing prerequisite KB2919355.
5. Download the applicable package from Microsoft’s Windows 10 Universal C Runtime Download Center page.
6. Select the package matching both the operating system and application environment.
7. Install it.
8. Restart Windows.
9. Test the affected program.

The Download Center package contains WindowsUCRT.zip with architecture-specific .msu files. Examples include:

Windows6.1-KB3118401-x86.msu
Windows6.1-KB3118401-x64.msu
Windows8.1-KB3118401-x86.msu
Windows8.1-KB3118401-x64.msu

Do not install an x64 package merely because the computer has a 64-bit processor. The package must match the operating system, while the application still needs the correct runtime architecture.

If the legacy update refuses to install, check the service pack and servicing prerequisite before trying another package. On unsupported systems, a modern application may require components that the old operating system cannot reliably provide. In that case, upgrading Windows or installing an application version that supports the existing system may be the durable solution.

Fix 6: Check antivirus quarantine

Security software can remove an application-local runtime file after an installation or update. This is more relevant when only one program fails and the error began immediately after antivirus activity.

1. Open Start.
2. Search for Windows Security.
3. Open Virus & threat protection.
4. Select Protection history.
5. Review recent detections.
6. Expand any detection associated with the affected application.
7. Confirm the file path and publisher before taking action.

Microsoft explains this process in Protection History in Windows Security.

Restore a quarantined file only when you have confirmed that it came from Windows or the legitimate application installer. Check the file’s Properties > Digital Signatures tab when a signature is present, and compare the path with the program’s normal installation directory.

If the file came from an untrusted download, do not restore it. Reinstall the application from its official source instead. If the same file is quarantined again, leave it blocked and investigate the application installer or contact the publisher.

Fix 7: Check the application’s architecture and local files

A 32-bit application can fail even when a 64-bit runtime exists in the Windows system directories. Conversely, a 64-bit program cannot use a 32-bit runtime as a substitute.

On 64-bit Windows, centrally deployed system libraries normally use these architecture-specific locations:

• %WINDIR%\System32 contains 64-bit system libraries.
• %WINDIR%\SysWOW64 contains 32-bit system libraries.

The names are counterintuitive, so do not infer the required architecture from the directory name alone. More importantly, do not manually copy a DLL between these directories.

An application may also load a private copy from its own installation directory. That copy must match the rest of the application’s runtime files. Replacing only one file can create a new mismatch with the companion UCRT components.

To investigate:

1. Note the full path of the failing executable.
2. Check whether the program is 32-bit or 64-bit.
3. Look for other api-ms-win-crt-*.dll files in the same application directory.
4. Use the application’s Repair option.
5. Reinstall the complete application if the local files are incomplete.
6. Contact the publisher if the program still fails after Windows and runtime repair.

If the error appears only for one Windows user account, also check per-user installation folders, permissions, application caches, and profile-specific configuration. That is a general troubleshooting possibility, not a cause established specifically for this DLL.

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Fix 8: Check driver and hardware-package installations

This file is not normally a device driver component. However, USB utilities, device-management suites, SDKs, recovery tools, and vendor installers can include native helper programs that depend on the UCRT.

If the failing program arrived with a hardware package or stopped working after a driver installation:

1. Right-click Start.
2. Select Device Manager.
3. Expand the category for the relevant device.
4. Right-click the device.
5. Select Update driver.
6. Choose Search automatically for drivers.
7. Restart Windows.
8. Launch the vendor utility again.

If the device utility itself is damaged, update or reinstall the complete vendor package from the manufacturer’s official source. Removing a device in Device Manager does not necessarily remove every associated vendor application file.

Outbyte Driver Updater can show which installed drivers need attention through its free scan, while driver installation is handled by the full version; the affected vendor application’s complete reinstall remains the definitive fix when its own files are damaged.

If the problem began after a driver change, use Device Manager > device > Properties > Driver > Roll Back Driver when that button is available and the previous driver is known to have worked. Do not remove unrelated drivers simply because the DLL error appeared nearby in time.

Windows Features are usually not the answer

Windows Features is not a general DLL repair menu. Do not enable random features because a program reports a missing runtime file.

You can open the feature list through:

1. Open Control Panel.
2. Select Programs.
3. Choose Turn Windows features on or off.
4. Review the feature list.

Use this area only when the application’s documentation specifically requires a Windows feature. Enabling a feature unrelated to the program will not replace the Universal C Runtime and may not change the loader error.

The same principle applies to .NET Framework, legacy components, and media features. They solve different dependency problems. Repair Windows components and the application runtime that the error actually identifies.

Do not use regsvr32 for this DLL

regsvr32 is intended for self-registering COM and OLE DLLs that provide a registration entry point such as DllRegisterServer. api-ms-win-crt-locale-l1-1-0.dll is a runtime/API-set forwarder, not a normal COM server.

There is no useful regsvr32 repair command for this file. Running commands such as these does not repair the UCRT:

regsvr32 api-ms-win-crt-locale-l1-1-0.dll

It may instead produce a message that the entry point is missing or that registration failed. Microsoft’s Regsvr32 documentation explains when the tool applies.

Why random DLL downloads are unsafe

Do not download api-ms-win-crt-locale-l1-1-0.dll from an unverified DLL collection site and copy it into System32, SysWOW64, or the application’s folder.

That approach can fail because:

• The file may contain malware or have been modified.
• The download may be for the wrong architecture.
• The file may belong to a different Windows build.
• The named DLL may only be the first dependency that failed.
• Other UCRT files may be missing or mismatched.
• The application may need its own complete runtime set.
• A copied file can hide the real Windows servicing problem.

Use Windows Update, Microsoft’s official UCRT package, Microsoft’s Visual C++ Redistributable downloads, or the application’s official installer. Microsoft supports application-local deployment only as a developer deployment scenario using a matching UCRT file set, not as a casual end-user repair method.

Fix 9: Use System Restore when the timing is clear

System Restore is useful when the error began immediately after a known update, cleanup utility, software installation, or driver change and a suitable restore point exists.

1. Press Win + R.
2. Enter:

rstrui.exe

1. Press Enter.
2. Select a restore point created before the error began.
3. Review the affected programs and drivers.
4. Start the restore.
5. Allow Windows to restart.
6. Test the application.

System Restore can roll back system files, registry settings, and installed programs, but it does not remove personal files. Microsoft provides more information in System Restore.

Do not use an old restore point merely because it exists. Choose this route when the timing of the failure clearly matches a system change.

If none of the fixes worked

At this point, identify whether the failure belongs to Windows or to one application.

Record:

• The exact error text.
• The affected executable and its installation path.
• Whether the executable is x86, x64, or ARM64.
• The Windows edition and architecture.
• Whether other programs fail with api-ms-win-crt-*.dll errors.
• Whether the application contains local UCRT files.
• The result of Windows Update, DISM, and SFC.
• Any recent antivirus quarantine event.
• Any recent application, driver, or Windows update.

If Windows Update, DISM, and SFC complete successfully but only one program fails, reinstall that program and contact its publisher. SFC and DISM can repair Windows components, but they cannot prove that a third-party application’s installation is complete.

If several applications fail after component repair, check disk health, review Windows servicing errors, and consider an in-place Windows repair using matching installation media. Use Microsoft’s repair-image instructions rather than replacing individual system DLLs.

Prevention

Keep Windows Update enabled and restart after major updates. When installing software, use the publisher’s official installer and allow its prerequisite checks to complete.

For programs that offer both 32-bit and 64-bit builds, install the build that matches the software you actually use. Keep the x86 Visual C++ Redistributable when you run 32-bit programs on 64-bit Windows.

Do not remove Visual C++ Redistributables indiscriminately. Multiple generations can be required by different applications.

When antivirus software quarantines a runtime file, verify the source and path before restoring anything. If an application update repeatedly loses the same file, reinstall the complete application and report the behavior to its publisher.

FAQ

Is api-ms-win-crt-locale-l1-1-0.dll a virus?

The filename identifies a legitimate Microsoft Universal C Runtime API-set component, but a filename alone does not prove that a particular copy is genuine. Check its location, digital signature, and installation source. A copy in an unusual user-writable folder deserves investigation.

Does this file belong to Windows or to a program?

Both situations are possible. The UCRT is part of Windows 10 and later and is serviced by Windows. A program may also install an application-local copy with its own files. The copy that triggered the error is determined by the program’s loader path.

Should I download the DLL separately?

No. Install Windows updates, repair the Windows component store, install the matching Visual C++ Redistributable, or repair the affected application from an official source.

Do I need x86 or x64?

Use x86 for a 32-bit program and x64 for a 64-bit program. A 64-bit Windows computer can legitimately need both packages.

Will reinstalling Visual C++ fix the error on Windows 11?

It may fix a missing application prerequisite, but it is not guaranteed to repair a corrupted Windows UCRT. On Windows 10 and Windows 11, run Windows Update and, when necessary, DISM followed by SFC.

Why does the error mention a locale DLL?

The API-set exposes locale-related C-runtime functions used by applications. It does not mean that a Windows language pack is missing.

Can I copy the file from another PC?

Do not do this. Windows builds, architectures, dependencies, and application-local runtime sets can differ. Repair the correct package through Microsoft or reinstall the application.

Can I register it with regsvr32?

No. It is not a self-registering COM/OLE server. regsvr32 is not a repair method for this runtime/API-set component.

What if the message says “The specified module could not be found”?

That wording can identify a missing dependency rather than the named DLL itself. Repair the complete runtime and application installation, then investigate neighboring runtime files if the problem continues.

What is the safest first step?

Install all available Windows updates, restart, and test the application. If the error remains, run DISM followed by SFC, then repair the affected application and install the Visual C++ package matching its architecture.

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