Start with this diagnostic checklist
The api-ms-win-core-timezone-l1-1-0.dll error usually appears when a specific application or game cannot load a Windows API contract or one of its runtime dependencies. Before changing anything, record:
- The exact program or game that fails
- The complete error wording
- Whether it happens when launching, installing, updating, or opening a particular feature
- Whether one application fails or several unrelated applications fail
- Your Windows version and build
- Whether the program is 32-bit or 64-bit
- Whether the problem began after an application update, Windows reinstall, disk cleanup, antivirus quarantine, or failed runtime installation
Press Win+R, type winver, and press Enter. Windows 10 and Windows 11 should follow the Windows repair path below. Windows 7, Windows 8, and Windows 8.1 may need the Universal CRT compatibility package or a newer supported version of the application.
What this filename actually means
api-ms-win-core-timezone-l1-1-0.dll is a Microsoft API-set contract name. It represents Windows time-zone and system/file-time functions, including GetTimeZoneInformation, FileTimeToSystemTime, and SystemTimeToTzSpecificLocalTime. Microsoft lists this contract as introduced with Windows 10 build 10.0.10240 in its Win32 API requirements table.
This is different from an ordinary third-party DLL. API-set names are stable contracts that the Windows loader maps to physical implementation DLLs through the API-set schema. The name may therefore be a virtual alias rather than a normal standalone file that should be downloaded, registered, or copied into a system folder. Microsoft explains this mapping in its documentation on Windows API sets and API-set loader operation.
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An application can still contain an API-set forwarder in its own installation directory. That does not prove the application developer created a unique implementation of the Windows API. It means the program, its Universal CRT files, or its installer expects the Windows loader to resolve that contract.
Fix 1: Repair the affected application first
If only one program fails, start with that program. This is the quickest path and is especially important when the error began after an update or when the application has its own launcher and prerequisites.
Use the application’s repair option
- Close the error message and exit the application from the notification area if it is still running.
- Open Settings with Win+I.
- Select Apps, then Installed apps.
- Find the affected program.
- Select the three-dot menu beside it.
- Choose Advanced options, if available.
- Select Repair and wait for Windows to finish.
- Start the program again.
If there is no Repair option, open the program’s launcher or installer. Look for Repair, Verify files, Scan and repair, or Install prerequisites. For a game, use the launcher’s file verification feature rather than replacing individual files.
If repair does not help:
- Uninstall the program from Settings > Apps > Installed apps.
- Restart Windows.
- Download the installer only from the application publisher or its official store.
- Install the program again.
- Restart once more if the installer requests it.
A clean reinstall is more reliable than copying a file into the application directory because it restores the application’s complete dependency set and preserves the correct architecture.
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Fix 2: Install Windows updates, then restart
On Windows 10 or Windows 11, pending servicing updates can affect system components used by applications.
- Press Win+I.
- Open Windows Update.
- Select Check for updates.
- Install every available update.
- Restart the PC, even if Windows does not immediately require it.
- Launch the affected program again.
Use Microsoft’s Windows Update instructions if the update process itself reports an error.
If updates cannot install, fix Windows Update before repeatedly reinstalling the application. Third-party security software can sometimes interfere with update operations, but do not assume antivirus is responsible for this exact filename without checking its history.
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Fix 3: Repair Windows components with DISM and SFC
Use this step when multiple applications fail, when the error appeared after a failed update or disk problem, or when Windows components may be damaged.
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- Open Start and type
Command Prompt. - Right-click Command Prompt.
- Select Run as administrator.
- Select Yes at the User Account Control prompt.
- Run this command:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Wait for it to complete. Do not close the window if progress appears to pause.
- After DISM finishes, run:
sfc /scannow
- Wait until verification reaches 100 percent.
- Restart Windows.
- Test the affected application.
Microsoft recommends running DISM before SFC in its system file repair instructions.
If SFC reports that it repaired files, test the program after restarting. If it reports that it found no integrity violations and only one application fails, return to the application repair path. SFC cannot correct an incorrectly packaged application-local runtime.
Repeating DISM and SFC without knowing what changed can make troubleshooting slow and confusing. Outbyte PC Repair can scan for issues that are difficult to identify manually; its free scan shows what it found, while repair is performed by the full version. Reinstalling the affected application remains the definitive fix when its own files or prerequisites are incorrectly packaged.
Fix 4: Install the correct Universal CRT or Visual C++ runtime
The Universal CRT contains ucrtbase.dll and API-set forwarders named api-ms-win-*.dll. Microsoft documents the Universal CRT deployment model, including compatibility deployment for older Windows versions.
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Use Microsoft’s latest supported Visual C++ Redistributable downloads. Choose the package according to the application, not only the operating system:
vc_redist.x86.exefor 32-bit applicationsvc_redist.x64.exefor 64-bit applications on x64 Windowsvc_redist.arm64.exefor ARM64 applications or devices
A 32-bit program needs the x86 runtime even on a 64-bit PC. If you use both 32-bit and 64-bit applications, installing both x86 and x64 packages may be appropriate.
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To repair the package:
- Download the official installer from Microsoft.
- Run it.
- Accept the license terms.
- If Repair appears, select it.
- Allow setup to finish.
- Restart Windows.
- Try the application again.
Microsoft states that Visual C++ runtimes from Visual Studio 2015, 2017, 2019, and 2022 are binary-compatible with the current v14 redistributable, subject to operating-system support. The current package is not a guarantee of support for Windows 7 or other older systems.
Fix 5: Check older Windows versions
If winver shows Windows 7, Windows 8, or Windows 8.1, the application may require API-set and Universal CRT components that were introduced for newer Windows releases.
Microsoft identifies Windows Update as the preferred central deployment method for the older-Windows Universal CRT and documents the initial compatibility update as KB2999226. Use the official Universal CRT deployment guidance and the application publisher’s prerequisite installer.
Then:
- Install all available updates for the operating system.
- Restart the PC.
- Install the correct x86 or x64 Visual C++ package for the program.
- Restart again.
- Repair or reinstall the application.
If the application officially requires Windows 10 or Windows 11, the reliable solution is to upgrade to a supported operating system or install an older application release that supports the current system. Installing a newer redistributable cannot add every newer Windows API contract to an unsupported operating system.
Fix 6: Check antivirus quarantine
An antivirus product may quarantine an application file or runtime component, particularly after an update. This is possible, but the error alone does not prove that antivirus removed the file.
- Open your antivirus or Windows Security application.
- Open Protection history, Quarantine, or Detection history.
- Search for the affected program, installer, or runtime.
- Check the file path, publisher, and digital signature.
- Restore the file only if the source and publisher are trustworthy.
- Update the security product.
- Run a full scan.
- Repair or reinstall the application from its official installer.
Do not create a broad antivirus exclusion just to suppress the error. If the same file is repeatedly quarantined, contact the application publisher or security vendor instead.
Confirm the program architecture
The runtime must match the executable:
- 32-bit application: install x86 dependencies
- 64-bit application: install x64 dependencies
- ARM64 application: install ARM64 dependencies where supported
To check a program’s architecture, open its installation folder, right-click the main executable, and select Properties. The Details tab may identify the product, but it does not always state the bitness. The application publisher’s system requirements or installer documentation is more reliable.
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Do not copy an x86 file into a 64-bit application folder, or vice versa. A wrong-architecture file can produce a different loader error, an invalid-image message, or prevent the application from starting.
Check Windows Features only for an application prerequisite
Windows Features are not a general repair for this API-set contract, but an older application may require an optional Windows component such as .NET Framework 3.5.
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- Press Win+R.
- Type
optionalfeatures. - Press Enter.
- Review the available features.
- Enable only the feature named by the application’s official requirements or installer.
- Select OK and allow Windows to obtain the required files.
- Restart if requested.
Do not enable unrelated features hoping they will restore api-ms-win-core-timezone-l1-1-0.dll.
Do not use regsvr32 or a DLL download site
regsvr32 is used for DLLs that provide a registration entry point such as DllRegisterServer. This API-set name is resolved by the Windows loader and is not normally repaired through registry registration. Running:
regsvr32 api-ms-win-core-timezone-l1-1-0.dll
is therefore not an appropriate fix. Microsoft describes the limitation in its DllRegisterServer troubleshooting documentation.
Do not download this file from a random DLL website or copy it into System32, SysWOW64, or the application folder. The replacement may be unsigned, malicious, corrupted, the wrong architecture, or incompatible with the Windows build. It may also hide the real problem: an unsupported operating system, damaged Windows servicing, or an incomplete application installation.
Use Windows Update, Microsoft’s official Visual C++ and Universal CRT packages, and the application publisher’s official installer instead.
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Driver checks are secondary
A driver reinstall is not a primary fix for this filename. Consider it only when the failure began with a broader game, graphics, or hardware installation problem.
To check for driver problems:
- Right-click Start.
- Select Device Manager.
- Expand the relevant category, such as Display adapters.
- Right-click the device.
- Select Properties and review the General and Driver tabs.
- Use Update Driver only with a driver supplied by Windows or the hardware manufacturer.
- Restart and test the application.
Outbyte Driver Updater can scan for outdated drivers when manually identifying hardware versions becomes repetitive; its free scan shows the detected issues, while driver installation is done by the full version. Driver repair should not replace application repair or Windows component repair for this error.
If nothing has worked
If updates, DISM, SFC, runtime repair, and application reinstall all fail:
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- Record the output of
winver. - Record the application name and version.
- Confirm whether the program is x86 or x64.
- Check Event Viewer by pressing Win+X, selecting Event Viewer, and opening Windows Logs > Application.
- Review the antivirus quarantine record.
- Test the application from a new local administrator profile to check for a damaged user profile.
- Consider System Restore only after confirming that backups and restore points are available.
If many unrelated applications report several api-ms-win-* errors, suspect Windows servicing, an unsupported operating system, disk corruption, or malware rather than one missing file. If only one application fails, focus on its installer, launcher, bundled runtime, and official prerequisites.
FAQ
Is this a normal DLL?
It is a real Microsoft API-set contract name, but it may not be a normal standalone DLL on disk. Windows maps the contract to an implementation through its API-set schema.
Is this the same as api-ms-win-crt-runtime-l1-1-0.dll?
No. The names are similar but identify different API-set contracts. The timezone contract covers time-zone and system/file-time APIs, while the CRT runtime contract is associated with Universal CRT runtime functions.
Should I install Visual C++ first?
Only after checking the Windows version, application architecture, and whether one or many programs fail. Visual C++ repair is useful for a UCRT-dependent application, but it will not repair every Windows API-set mapping problem.
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The loader reports the contract it could not resolve. “Missing” can mean an unavailable API contract, missing UCRT forwarder, unsupported Windows version, corrupted Windows component, or damaged application package.
Will SFC always restore it?
No. SFC can repair Windows-owned components when the component store is usable. It cannot fix an application that bundled an incomplete or incompatible runtime.
Can I register it with regsvr32?
No. API-set contracts are loader mappings, not ordinary registered COM or ActiveX libraries. Repair Windows, the runtime, or the affected application instead.
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