api-ms-win-core-datetime-l1-1-0.dll is a Microsoft Windows API-set contract, not a game DLL or a Visual C++ Redistributable file. If Windows reports that it is missing or cannot be loaded, repair Windows first, then repair the specific application if only one program is affected.
What this file actually does
The unusual filename identifies an API-set contract. Windows uses API sets as stable names that the loader maps to the underlying operating-system implementation. This file belongs to the Windows API architecture and covers core date and time-related functions.
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It is not normally something you download separately. Microsoft documentation lists the file in Windows servicing packages, including Windows 7 updates, and related API-set files can appear in Windows system locations such as System32 or System32downlevel. The exact location, version, and architecture depend on the Windows release and installed updates. Microsoft’s Windows API-set documentation
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- A damaged Windows component store
- An incomplete Windows update
- A program built for a newer Windows release
- A damaged or incomplete application installation
- A 32-bit and 64-bit architecture mismatch
- An antivirus quarantine
- Another unresolved dependency
- An incorrect DLL bundled beside the application
Microsoft’s Windows 7 servicing manifest explicitly includes this file for both x86 and x64 packages. Do not treat an old file listing or a third-party version report as the correct file version for every Windows installation. Microsoft’s Windows 7 update manifest
Cause-by-symptom table
| What you observe | Most likely cause | Start here |
|---|---|---|
| Several programs fail with similar DLL errors | Damaged or missing Windows components | Windows Update, DISM, then SFC |
| Only one game or application fails | Damaged installation or private application DLL | Repair, verify, or reinstall that program |
| The problem began after an update | Incomplete servicing or incompatible application | Restart, install pending updates, then repair Windows |
The error also names vcruntime140.dll or msvcp140.dll |
Visual C++ runtime dependency | Install the official runtime matching the application |
| Defender reports a quarantined DLL | Security software intervention | Review Protection history before restoring anything |
| The application is old and Windows is recent | Application compatibility or bundled DLL issue | Update or reinstall the application |
| A 32-bit application fails on 64-bit Windows | Wrong runtime or application-local DLL | Use the x86 dependency and repair the application |
| “The specified module could not be found” appears | A dependent module may be missing | Repair Windows and inspect the application dependencies |
Fix 1: Install Windows updates, then restart
Start with the operating system because this is a Windows API-set file.
- Press
Win+Ito open Settings. - Select Windows Update.
- Select Check for updates.
- Install all applicable updates.
- Restart the computer, even if Windows does not insist on a restart.
- Launch the affected application again.
If Windows Update reports that everything is current but the error remains, continue with DISM and SFC. If the computer runs Windows 7 or another older release, install the applicable service and security updates through Microsoft’s supported update channels. A newer application may require an API contract or runtime that the older operating system does not fully support.
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This is the primary repair sequence when multiple programs fail or the file is absent from the expected Windows system location. Microsoft recommends running DISM before System File Checker because DISM repairs the component store that SFC uses as a source.
- 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. Do not close the window while it is working.
- After DISM completes successfully, run:
sfc /scannow
- Wait until verification reaches 100 percent.
- Restart Windows and test the affected program.
A successful SFC result says that Windows Resource Protection did not find integrity violations, or that it found and repaired damaged files. If SFC says it repaired files, restart before testing.
If DISM cannot obtain repair files from Windows Update, use a matching Windows installation source rather than copying an isolated DLL. The source must correspond closely to the installed Windows edition, release, and architecture. Microsoft documents the advanced /Source procedure in its Windows image repair guidance.
Repeating SFC and DISM without knowing what changed can make troubleshooting slow. Outbyte PC Repair can scan for the condition behind the failure; its free scan shows what it identifies, while repair is handled by the full version. It is optional, and Windows repair remains the correct first-line method.
Fix 3: Repair or reinstall the affected application
If every other program works and only one game or application shows the error, the application installation is the stronger suspect.
First look for a built-in repair option:
- Open Settings with
Win+I. - Select Apps.
- Select Installed apps or Apps & features, depending on your Windows version.
- Find the affected application.
- Select its three-dot menu.
- Choose Advanced options, if available.
- Select Repair.
- Test the application.
- If it still fails, return to the same screen and select Reset, if the application supports it.
Reset can remove application settings or locally stored data, so use it after Repair.
For a desktop program without a Repair option:
- Download the installer from the application developer’s official source.
- Close the application and its launcher.
- Run the installer.
- Choose Repair if offered.
- Otherwise uninstall the application from Settings > Apps.
- Restart Windows.
- Install the current supported version.
- Launch it once using Run as administrator if the installer or application requires elevated access.
For a game, open its official launcher and use its Verify, Verify integrity, Scan, or Repair files command where available. This restores the application’s own files without relying on an arbitrary DLL download.
Pay attention to the application’s supported Windows versions. A program built for a newer Windows release may not run correctly on an older operating system even after the application is reinstalled.
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Fix 4: Check 32-bit and 64-bit compatibility
A 32-bit application on 64-bit Windows normally needs 32-bit dependencies. Installing only a 64-bit runtime does not repair every 32-bit application failure.
To identify the application architecture, check the developer’s system requirements or installation documentation. You can also inspect the application’s installation location, although the folder name alone is not conclusive.
- A 32-bit application generally needs the x86 Visual C++ package.
- A 64-bit application generally needs the x64 package.
- ARM64 applications require the ARM64 package where applicable.
Do not copy files between System32, SysWOW64, and an application directory. On 64-bit Windows, those system folders have architecture-specific roles, and manual replacement can create another loader failure.
If the error also names vcruntime140.dll, msvcp140.dll, or Universal CRT files, install or repair the official Microsoft Visual C++ Redistributable. Use the package architecture required by the application, not simply the architecture of Windows. The official direct packages include x86, x64, and ARM64.
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Visual C++ is a separate dependency. It does not own api-ms-win-core-datetime-l1-1-0.dll, so installing it alone is not the normal fix for this file.
Fix 5: Check antivirus quarantine
Microsoft Defender or another antivirus product may have quarantined a file from the application directory.
- Open Windows Security from the Start menu.
- Select Virus & threat protection.
- Select Protection history.
- Review recent detections.
- Expand any item associated with the affected program.
- Check its path and detection details.
- Restore it only if you can confirm that it came from a trusted Windows or application installation.
Do not restore an unknown DLL merely because its filename resembles a Windows component. If the file is suspicious, leave it quarantined, run a full Microsoft Defender scan, and reinstall the application from its official installer. Microsoft explains these decisions in its Protection History guidance.
Fix 6: Inspect application-local DLL conflicts
Windows searches application and system locations according to DLL search rules. A private DLL beside the program can override or conflict with the copy Windows expects.
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Do not delete random files from System32. Instead:
- Close the affected application.
- Open its installation folder from the launcher or shortcut properties.
- Look for an unofficial or recently added copy of
api-ms-win-core-datetime-l1-1-0.dll. - If the application contains its own DLL bundle, use the launcher’s Verify or Repair command.
- If no repair option exists, reinstall the application.
- Test again before adding any replacement file.
A program that says “The application was unable to start correctly” or “The specified module could not be found” may have a damaged parent DLL or another missing dependency. The displayed filename can be the first unresolved item rather than the complete cause.
Independent reader supportYour contribution helps us test, update, and keep practical guides available for everyone.Fix 7: Update a driver only when the application identifies one
Driver reinstallation is not a standard repair for this Windows API-set file. Consider it only if the failing application is a driver-dependent package and its own installer or logs identify a damaged graphics, audio, storage, or device driver.
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For a normal Device Manager reinstall:
- Right-click Start.
- Select Device Manager.
- Expand the category for the affected device.
- Right-click the device.
- Select Uninstall device.
- Restart Windows.
- Install the current driver from the device manufacturer or computer manufacturer.
- Restart again and test the application.
Do not remove a working driver just because this DLL appears in an error message. Outbyte Driver Updater can scan for outdated drivers; its free scan identifies what it finds, while driver installation is handled by the full version. Use it only as an optional convenience, and follow the hardware manufacturer’s installer when the application names a specific driver.
Do not download or register this DLL
Avoid DLL download websites and random forum attachments. An isolated copy may have the wrong Windows build, wrong architecture, altered contents, or malware, and it may not repair the damaged component that caused the error.
Do not run regsvr32 on this file. regsvr32 is for self-registering components that expose registration entry points such as DllRegisterServer; an API-set stub is not a normal COM or ActiveX component. Registration will not restore Windows and may produce an entry-point error. Microsoft’s DllRegisterServer documentation
Use Windows Update, DISM, SFC, the application’s official installer, and Microsoft’s official runtime downloads instead.
If the error still remains
If DISM and SFC complete but the program still fails:
- Confirm whether every program fails or only one.
- Check the application’s supported Windows versions.
- Repair or reinstall the application again from its official installer.
- Check for quarantined files.
- Remove unofficial application-local DLL copies through a clean reinstall.
- Run a full Microsoft Defender scan.
- Check disk health if Windows reports recurring file corruption.
- Use System Restore if the failure began immediately after a driver, update, or software change.
To start System Restore, press Win+R, type rstrui.exe, and press Enter. Select an appropriate restore point, review the affected programs, and complete the wizard if the restore point predates the failure. Microsoft System Restore guidance
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Is this a Visual C++ file?
No. It is a Windows API-set contract. Visual C++ may be a separate dependency if the error also names files such as vcruntime140.dll or msvcp140.dll.
Should I copy it into System32 or SysWOW64?
No. Manual copying can install the wrong architecture or introduce a malicious file. Repair Windows through DISM and SFC instead.
Does this file belong to DirectX or .NET?
No. It is part of the Windows API-set architecture, not a DirectX or .NET runtime download.
Why does only one game fail?
The game may have a damaged installation, an incompatible bundled DLL, or a missing dependency. Verify or reinstall that game before changing system files.
Do these 3 things before closing this tab:
1Clear out junk files and repair common Windows errors2Fix the driver behind crashes, sound loss and screen glitches3Repair Windows errors before they cause bigger problemsCan I use regsvr32?
No. This is not a self-registering COM component, so regsvr32 is not an appropriate repair.
What if I use Windows 7?
Install applicable Microsoft servicing updates and check whether the application supports Windows 7. A newer program may require operating-system components unavailable on that release. Microsoft also published a Universal C Runtime update for earlier Windows versions, but that runtime is separate from ownership of this API-set file. Universal C Runtime update
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