The api-ms-win-crt-runtime-l1-1-0.dll message usually means Windows cannot find or load part of the Universal C Runtime required by the application you are opening. The dependable fix is to complete Windows Update, then install or repair the official Microsoft Visual C++ Redistributable, selecting the architecture the application needs. On 64-bit Windows, that can mean installing both the x64 and x86 packages. Do not download a single DLL from an unofficial website or copy it into System32; that can leave the underlying runtime, update, and registration problems untouched.
What the error means
api-ms-win-crt-runtime-l1-1-0.dll is an API-set DLL associated with the Windows Universal C Runtime. It is not normally a standalone component that you should hunt for and replace manually. Programs compiled against Microsoft’s C and C++ runtime expect Windows to provide this API set through the operating-system runtime and Visual C++ support files.
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When the runtime is missing, outdated, incompletely updated, or corrupted, Windows may show messages such as “The program can’t start because api-ms-win-crt-runtime-l1-1-0.dll is missing from your computer” or report that the application cannot start. The application itself may be perfectly intact; the failure occurs before it can launch because a required runtime dependency is unavailable.
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Microsoft Q&A guidance identifies an unupdated Windows installation and missing, outdated, or corrupted Visual C++ 2015 libraries as the usual causes. Autodesk Support likewise lists a corrupted Visual C++ installation and missing Windows updates among the recurring causes of this message.
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Why it happens
Windows updates are incomplete
The Universal C Runtime was delivered through Windows servicing. If a computer has been offline, updates were interrupted, or an update is waiting for a restart, the API-set files may not be present in the state an application expects. On older Windows releases, the Universal C Runtime update is identified as KB2999226.
The Visual C++ runtime is damaged or absent
Many desktop games, launchers, utilities, and creative applications depend on the Microsoft Visual C++ Redistributable. A failed installation, an interrupted update, disk corruption, or removal of shared components can make the runtime unusable even when the application’s own files are present.
The wrong architecture was installed
Microsoft provides separate redistributables for 32-bit and 64-bit programs. The x86 installer is for 32-bit applications; the x64 installer is for 64-bit applications. A 64-bit edition of Windows can run programs built for either architecture, so a 64-bit computer may need both packages. Installing only x64 does not satisfy a 32-bit game or utility.
Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsOne application has its own damaged prerequisite
If the error appears for only one program, that program’s installer may have failed to deploy its prerequisites, or its bundled runtime may have become corrupted. In that case, the application vendor’s official installer and support process are safer than replacing a DLL by hand.
Before changing anything
- Write down the exact application that fails and the complete error text. The name helps you identify whether the program is likely to be 32-bit or 64-bit and gives its vendor useful diagnostic information.
- Check whether Windows reports a pending restart. Updates can be downloaded but not fully applied until you restart.
- Confirm which Windows edition you use. The procedure applies to Windows 11, Windows 10, Windows 8, and Windows 7, but the Settings labels differ between releases.
- Use only Windows Update, Microsoft’s redistributable installer, or the affected application vendor’s official installer. Avoid third-party DLL download sites.
Fix the error in the safest order
1. Complete Windows Update
- On Windows 11 or Windows 10, open Settings, choose Windows Update (under Update & Security on some Windows 10 builds), and select Check for updates.
- Install every applicable update offered, not just the first item that appears. If Windows asks for a restart, restart before checking again.
- After the restart, return to Windows Update and check a second time. Continue until Windows reports that no further applicable updates are waiting.
- On older Windows releases, install the updates offered through the operating system’s Windows Update control panel. If documentation for your release refers to the Universal C Runtime update, look for
KB2999226.
Windows Update is the first step because it can supply the Universal C Runtime components and the servicing changes that a redistributable installer expects. Retest the original application only after the update cycle and restart are complete.
2. Install the official Visual C++ Redistributable
- Obtain the Microsoft Visual C++ Redistributable recommended for the application, or use the application vendor’s official installer when it supplies one. For this error, support guidance commonly points to the Visual C++ 2015 runtime.
- Run the installer and allow it to finish. If Windows presents a repair or maintenance screen instead of a fresh installation, use that repair option first.
- Restart Windows after the installer completes, even if it does not explicitly require a restart. Then open the application that originally failed.
Do not treat a standalone DLL as a substitute for this package. The redistributable installs and services a group of related runtime components; copying one file cannot correct a missing update or a damaged package.
3. Install the architecture the program actually uses
| Package | Use it for | Important detail |
|---|---|---|
vcredist_x86.exe |
32-bit Windows applications | A 32-bit game or utility needs x86 even when Windows itself is 64-bit. |
vcredist_x64.exe |
64-bit Windows applications | Install this for a native 64-bit application on 64-bit Windows. |
| Both x86 and x64 | 64-bit Windows running software of both types | Installing both is appropriate when you use a mixture of 32-bit and 64-bit programs. |
The Microsoft Q&A guidance distinguishes these installers by architecture. If you are unsure which build the affected application uses, installing both official packages on 64-bit Windows avoids the common situation where x64 is present but the failing 32-bit program still lacks its runtime.
4. Repair an existing redistributable
- Open Settings and go to Apps > Installed apps (Windows 11) or Apps & features (Windows 10). On older releases, open Control Panel > Programs > Programs and Features.
- Look for the Microsoft Visual C++ Redistributable entry that matches the installed runtime and architecture. There may be separate x86 and x64 entries.
- Select Modify, Change, or the equivalent maintenance command, then choose Repair when offered.
- Let the process finish, restart Windows, and launch the original program again.
Repair is preferable to removing a working package because other applications may depend on it. It also tests whether the existing installation is merely damaged rather than absent.
5. Reinstall when repair does not work
- Return to the same list of installed programs and select the affected Visual C++ Redistributable entry.
- Choose Uninstall and complete the removal. If both x86 and x64 entries are damaged, address each one separately rather than assuming that removing one fixes the other.
- Restart Windows.
- Install the official redistributable packages again, selecting x86, x64, or both according to the application mix described above.
- Restart once more and retest.
Reinstalling replaces a broken package, but it does not replace missing Windows servicing. If the error returns immediately, go back to Windows Update and confirm that all applicable updates, including the Universal C Runtime update identified as KB2999226 on older releases, are installed.
6. Use the application vendor’s installer if one is supplied
Some games and professional applications include a prerequisite installer in their setup files or provide a current runtime package through their support page. Use that official workflow when Microsoft’s package is already repaired but the program still fails. Autodesk Support specifically recommends installing Windows updates and reinstalling Microsoft Visual C++ Redistributables for this class of problem, while inMusic Support gives the order of updating Windows, installing the Visual C++ Redistributable for Visual Studio 2015, and updating the Windows Universal C Runtime libraries.
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Which remedy addresses which problem?
| Remedy | What it addresses | When to choose it | What it cannot do |
|---|---|---|---|
| Windows Update | Missing Windows servicing and Universal C Runtime delivery | First response, especially on an older or recently reinstalled Windows system | It may not repair a separately corrupted Visual C++ package. |
| Microsoft Visual C++ Redistributable installer | Missing runtime files and package installation | After updates, or when the application vendor identifies Visual C++ as a prerequisite | Installing only x64 does not satisfy a 32-bit application. |
| Repair | Damage in an existing redistributable installation | The package is listed in Installed apps or Programs and Features | It cannot correct a Windows update that was never installed. |
| Uninstall and reinstall | A package that repair cannot restore | Repair fails or the installer remains unusable | It should not be used as a substitute for installing pending Windows updates. |
| Application vendor’s official installer | Missing prerequisites specific to one program | Only one application fails or the vendor supplies a bundled runtime | It cannot make an unofficial DLL download trustworthy. |
What not to do
Do not download a lone DLL from a random repository
Unofficial DLL sites can provide the wrong file version, the wrong architecture, or a file with an unknown trust history. Even a file that has the right name may not match the runtime expected by the application.
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Do not copy the file into System32
Manual copying bypasses Windows servicing and the redistributable installer. It can leave related runtime files, registration state, and update prerequisites inconsistent. The supported guidance points to Windows Update and Microsoft’s redistributable instead.
Do not delete other Visual C++ entries casually
Several applications can share a redistributable. Removing an entry without reinstalling the correct package can create new launch failures. Use Repair first, then reinstall deliberately if repair fails.
Troubleshoot the result
The message remains after Windows Update
Check that the update process actually completed and that you restarted afterward. Then repair or reinstall the Visual C++ Redistributable. Verify the architecture: a 32-bit application still requires x86 on 64-bit Windows. If the program’s installer includes its own prerequisite package, run that official installer next.
The installer reports that a newer version is already installed
Use the installed-apps maintenance entry and choose Repair. If Repair does not restore the runtime, uninstall the affected entry, restart, and reinstall the official package. Repeat the check for the other architecture when both x86 and x64 applications are used.
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Record the application version and error text, then use the vendor’s support or installer workflow. A single-program failure can indicate a damaged application prerequisite rather than a system-wide absence of the API set.
The error started after a Windows reinstall or on an older PC
Complete every available Windows update before installing application software. On older Windows releases, pay particular attention to the Universal C Runtime update referenced as KB2999226, then install the Visual C++ 2015 redistributable and restart.
The application still will not start after all supported steps
At that point, preserve the exact error message, Windows edition, whether the system is 32-bit or 64-bit, and which x86 or x64 packages you repaired. Give those details to the application vendor. Autodesk’s support guidance treats missing updates and corrupted Visual C++ installations as recurring causes, so confirming both areas helps support staff avoid repeating incomplete fixes.
Source-backed guidance
A Microsoft Q&A answer dated March 5, 2017, attributes this message to Windows not being updated or to Visual C++ 2015 libraries being corrupted, absent, or outdated. Autodesk Support, published August 3, 2026, lists “Corrupted installation for Visual C++” and “Missing Windows Updates” as causes and recommends Windows updates plus reinstallation of the Microsoft Visual C++ Redistributables. inMusic Support, modified June 9, 2026, gives the same practical order: install all Windows updates, install the Visual C++ Redistributable for Visual Studio 2015, and update the Windows Universal C Runtime libraries.
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Those recommendations converge on the same principle: restore the supported runtime and Windows servicing state rather than replacing one DLL in isolation.
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