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api-ms-win-core-libraryloader-l1-1-1.dll is a genuine Microsoft Windows API-set dependency, not a random game DLL. If Windows says it is missing, the visible filename may identify a broken dependency while the real fault is in Windows, the Universal CRT, or the application that requested it.
Identify what this file is
An API-set name is a contract used by Windows. It redirects an application’s API calls to the Windows DLL that implements them. That means the name can look like a normal DLL even though it is not necessarily a standalone file you should download and copy into a folder.
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Microsoft describes API-set names as virtual aliases for implementation DLLs. The Universal CRT also uses API-set forwarders named api-ms-win-*.dll alongside ucrtbase.dll.
| Question | Safe conclusion |
|---|---|
| Is it a Windows file? | It belongs to the Windows API-set and Universal CRT ecosystem. |
| Is it a normal application DLL? | No. The named contract may point to another Windows implementation file. |
| Is there one universal version or size? | No. Details vary by Windows build and architecture. |
| Should you download it separately? | No. Repair the application or Windows component that supplies the dependency. |
| Does the name prove the application is infected? | No. It is normally a loader or runtime dependency problem. |
The right repair depends on where the error appears:
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- During a Windows 7-to-Windows 10 upgrade, it may involve an old
wimgapi.dllbundled with the Upgrade Assistant. - When one program or game fails, the application installation or its runtime is the more likely problem.
- When several programs fail, Windows component corruption or a missing Universal CRT update becomes more likely.
- After antivirus activity, cleanup, migration, or an incomplete reinstall, quarantine or damaged files may be involved.
Fix the application first when only one program fails
If one program or game displays the error while other software works normally, do not begin by replacing Windows files.
Repair or reinstall the affected program
- Close the error dialog.
- Open Settings with
Win+I. - Select Apps, then Installed apps.
- Find the affected application.
- Select the three-dot menu and choose Advanced options, if available.
- Select Repair and wait for Windows to finish.
- Start the program again.
If there is no Repair option, uninstall the application from the same screen. Restart Windows, then reinstall it from the publisher’s official installer or the official game launcher.
For a game, open its launcher and use Verify, Verify integrity, Repair, or the equivalent file-checking command. The exact wording varies by launcher. A successful verification normally reports that files are valid or replaces damaged files. If the same error returns immediately, reinstall the application rather than copying a DLL into its folder.
If the program has both 32-bit and 64-bit builds, install the build that matches the application and its supported runtime. A 32-bit program can require x86 components even when Windows itself is 64-bit.
Install the correct Microsoft Visual C++ runtime
Applications built with Visual Studio 2015 or later may depend on the current compatible Microsoft Visual C++ Redistributable. Use Microsoft’s latest supported Visual C++ Redistributable downloads.
Install the architecture required by the failing application:
- Use the official x86 package for a 32-bit application.
- Use the official x64 package for a 64-bit application.
- Some 64-bit Windows systems need both packages because they run both 32-bit and 64-bit applications.
To install it:
- Download the required package from Microsoft.
- Right-click the installer and select Run as administrator.
- Accept the license terms.
- Choose Install or Repair if the runtime is already present.
- Restart Windows.
- Launch the affected application again.
If this fixes the program, the missing contract was likely being requested through an incomplete or unavailable runtime. If it does not, keep the runtime installed and continue with application repair and Windows component repair. Do not remove older Visual C++ Redistributable generations, because unrelated programs may depend on them.
On older Windows installations, the Universal CRT may also be missing or incomplete. Microsoft identifies KB2999226 as the initial Universal CRT update and KB3118401 as a later update, with additional servicing updates afterward. Windows Update is the preferred deployment route rather than manually copying runtime files.
Install pending Windows updates
A missing API-set contract can follow incomplete servicing, especially on older Windows.
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- Press
Win+I. - Open Windows Update.
- Select Check for updates.
- Install all available updates.
- Restart when requested.
- Check again until Windows reports that no further updates are available.
On Windows 7, bring the system to its required service-pack and update level before attempting to install a newer Visual C++ runtime. Windows 10 support ended on October 14, 2025, so treat old Windows 7-to-Windows 10 upgrade reports as historical troubleshooting cases, not as a recommendation to keep using unsupported software.
Repair Windows component files
Use this path when several applications fail, the error followed a failed update, or Windows shows other integrity problems.
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Run DISM on supported Windows versions
On Windows 8.1 and later:
- Open Start.
- Type
Command Prompt. - Right-click Command Prompt and choose Run as administrator.
- Enter:
DISM.exe /Online /Cleanup-Image /RestoreHealth
- Wait for the operation to complete.
- Restart Windows.
DISM can take time and may appear to pause. Let it finish. If it reports that the component store was repaired, restart and test the application.
Windows 7 does not support these DISM options in the same way. Use its appropriate servicing and update path instead of forcing the command.
Run System File Checker
After DISM, or directly on a supported Windows installation:
- Open an elevated Command Prompt as above.
- Run:
sfc /scannow
- Wait until verification reaches 100 percent.
- Restart Windows.
- Test the application again.
If SFC says it repaired files, repeat the test after restarting. If it reports that some files could not be repaired, run DISM first where supported, restart, and run SFC again. Microsoft’s System File Checker guidance explains the repair process.
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Check antivirus quarantine
If the message began immediately after a security scan:
- Open your antivirus application.
- Open Protection history, Quarantine, or Detected threats.
- Look for a quarantined Windows or application file.
- Confirm the file belongs to the correct installation and is digitally signed by Microsoft or the application publisher before restoring it.
- If you cannot verify it, leave it quarantined.
- Run a full security scan.
- Repair Windows or reinstall the application from its official source.
Do not disable security software merely to obtain a DLL. A quarantined file may be damaged, altered, or unrelated to the API-set name shown in the error.
Handle the old Windows 7 upgrade case carefully
A well-known historical case occurred during a Windows 7-to-Windows 10 Upgrade Assistant run, sometimes with error 0x8007007e. Microsoft Q&A users reported that the updater’s bundled file was incompatible or outdated:
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C:Windows10Upgradewimgapi.dll
The reported workaround was to back up that file and replace it with the copy from:
C:WindowsSystem32wimgapi.dll
This is a narrowly scoped, community-reported workaround, not a universal Microsoft-supported repair for every occurrence of this error.
If you are reproducing that exact legacy upgrade failure:
- Close the Upgrade Assistant.
- Back up the entire
C:Windows10Upgradefolder. - Confirm that the source file is the local Windows file at
C:WindowsSystem32wimgapi.dll. - Do not download
wimgapi.dllfrom another site. - Replace only the updater-folder copy, not the file in
System32. - Retry the upgrade.
A safer modern approach is to use current Microsoft installation media or supported upgrade tooling. The Microsoft Q&A case documents the historical report, but it does not prove that every current error has the same cause.
Roll back a recent system change
If the error started after a driver, update, or application installation:
- Press
Win+R. - Enter:
rstrui.exe
- Press Enter.
- Choose a restore point dated before the failure.
- Select Next, review the affected programs, and choose Finish.
- Restart Windows and test the application.
System Restore rolls back system files, registry settings, installed programs, and drivers. It does not normally remove personal files.
If diagnostics identify a driver as the initiating change, update or reinstall that driver through Settings > Windows Update > Advanced options > Optional updates, or through Device Manager:
- Right-click Start and open Device Manager.
- Expand the relevant device category.
- Right-click the device.
- Choose Update driver or Uninstall device.
- Restart Windows if you uninstall it.
- Install the driver from the device manufacturer if Windows does not restore it.
This filename is not itself a driver-specific component. Do not reinstall random drivers merely because the error mentions a DLL.
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Do not download the DLL from a random website
A downloaded replacement can have the wrong architecture, Windows build, or trust status. It may also introduce malware, fail to resolve the real dependency, or create a second loader error.
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Do not copy an unverified file into:
C:WindowsSystem32C:WindowsSysWOW64- An application directory
- A game directory
Use Windows Update, Microsoft runtime packages, Windows repair commands, or the application’s official installer instead.
Do not use regsvr32 for this file
regsvr32 is intended for self-registering DLLs and OCXs that expose registration entry points such as DllRegisterServer. API-set forwarders and runtime dependencies generally do not use that mechanism.
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It can produce a registration error without changing the underlying problem. Microsoft’s regsvr32 guidance explains why registration failures occur.
Do not change Windows Features at random
Opening Control Panel > Programs > Turn Windows features on or off will not normally restore an API-set contract. Use Windows Features only when the application’s own documentation specifically requires an optional Windows component, such as a legacy framework. Enabling unrelated features is not a substitute for repairing the runtime or application.
If the error remains
Collect these details before escalating:
- The exact error dialog text and error code
- The application or game executable name
- Windows version and build from
winver - Whether Windows is 32-bit or 64-bit
- Whether the failing application is 32-bit or 64-bit
- Whether the issue began after an update, cleanup, antivirus action, migration, or reinstall
- The application and Windows directories where related files exist
- Relevant entries from Event Viewer > Windows Logs > Application
- Whether DISM and SFC completed successfully
If only one application still fails after a clean reinstall, test a new Windows user account or the application’s clean profile. If several applications fail after DISM and SFC, the API-set name may only be the first unresolved dependency, and Windows recovery or repair installation may be necessary.
FAQ
Is this file part of Windows or Visual C++?
It is a Windows API-set contract associated with the Universal CRT and Windows runtime ecosystem. A Visual C++ Redistributable can supply runtime components an application needs, but installing it is not guaranteed to repair every Windows API-set error.
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1Scan for outdated or missing drivers - takes under a minute2Clear out junk files and repair common Windows errors3Fix the driver behind crashes, sound loss and screen glitchesWhy does the message name this file when wimgapi.dll or ucrtbase.dll is damaged?
The loader reports the dependency it could not resolve. API-set contracts redirect calls to implementation DLLs, so the named contract may be the visible failure while another dependency is incompatible, missing, or damaged.
Should I install both x86 and x64 runtimes?
Install the architecture required by the failing application. A 32-bit program needs x86 components even on 64-bit Windows. Installing both can be appropriate when the computer runs applications of both architectures.
Is this mainly a Windows 7 problem?
The most recognizable historical case was the Windows 7-to-Windows 10 Upgrade Assistant failure. Modern Windows 10 and Windows 11 systems can still show related loader errors after application corruption, missing runtimes, or Windows component damage.
Can I fix it by copying the file from another computer?
Do not do that. Builds, architectures, signatures, and dependency relationships may differ. Repair the originating application or Windows installation with official Microsoft methods.
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What is the safest first step?
If one application fails, repair or reinstall that application from its official source. If several applications fail, install pending Windows updates, run DISM where supported, then run sfc /scannow.
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