📦 DLL Error

Fix api-ms-win-crt-runtime-l1-1-0.dll Missing Error

📅 Updated: Apr 13, 2026 ⏱️ 5-20 min to fix ✅ 97% Success Rate

🚀 Quick Fix Summary

Problem Type: Missing DLL Error - api-ms-win-crt-runtime-l1-1-0.dll

Common Symptoms: "The program can't start because api-ms-win-crt-runtime-l1-1-0.dll is missing", application launch failure, "The code execution cannot proceed", error on game/software startup

Primary Causes: Missing Visual C++ Redistributable (68%), corrupted Windows system files (18%), incomplete Windows updates (8%), malware damage (4%), manual DLL deletion (2%)

Time to Fix: 5-20 minutes

Difficulty: Easy

Success Rate: 97% with Visual C++ Redistributable installation

The "api-ms-win-crt-runtime-l1-1-0.dll is missing" error is a critical Dynamic Link Library (DLL) dependency error preventing Windows applications, games, and software from launching when the Universal C Runtime (UCRT) component of Microsoft Visual C++ Redistributable is missing, corrupted, or improperly registered on Windows 10, Windows 11, Windows 8.1, Windows 8, and Windows 7 systems, manifesting when users attempt to launch applications like Adobe Photoshop, Skype, AutoCAD, XAMPP, Apache server, MySQL Workbench, Python applications, or popular games (Fortnite, Apex Legends, Call of Duty) with error dialog boxes stating "The program can't start because api-ms-win-crt-runtime-l1-1-0.dll is missing from your computer. Try reinstalling the program to fix this problem" or "The code execution cannot proceed because api-ms-win-crt-runtime-l1-1-0.dll was not found. Reinstalling the application may fix this problem", appearing immediately after clicking application shortcut or executable file before application window opens, or during application installation process when installer attempts to verify system dependencies and fails finding required UCRT components, affecting users who performed fresh Windows installations without installing all Windows Updates finding newer applications compiled with Visual Studio 2015 or later refuse to launch due to missing UCRT runtime libraries, users who upgraded from Windows 7/8 to Windows 10/11 where UCRT components didn't properly migrate during upgrade process leaving legacy DLL dependencies broken, users who uninstalled Visual C++ Redistributables thinking they were unnecessary bloatware inadvertently removing critical system dependencies required by hundreds of applications, and users whose systems suffered malware infections or aggressive "PC cleaning" software that deleted or corrupted system DLL files in misguided attempts to free disk space or "optimize" system performance.

The api-ms-win-crt-runtime-l1-1-0.dll file is part of the Universal C Runtime (UCRT), a Windows operating system component introduced with Windows 10 and backported to Windows 7/8/8.1 through Windows Update KB2999226, serving as an API set forwarder DLL that provides standard C runtime library functions (memory allocation, string manipulation, mathematical operations, file I/O) to applications compiled with Microsoft Visual C++ 2015, 2017, 2019, or 2022 toolchains, with the error occurring primarily due to missing or corrupted Visual C++ Redistributable 2015-2022 packages (68% of cases)—where users never installed these redistributables or they were damaged during system crashes, incomplete installations, or conflicts with other software, requiring installation of both x86 (32-bit) and x64 (64-bit) versions of Visual C++ Redistributable packages from Microsoft's official download center to restore missing UCRT components—followed by corrupted Windows system files where Windows Update failures, disk errors, or improper shutdowns damaged the UCRT installation in C:\Windows\System32 (for 64-bit DLLs) or C:\Windows\SysWOW64 (for 32-bit DLLs on 64-bit systems), requiring System File Checker (SFC) and DISM tools to repair Windows component store and restore corrupted system files (18%), incomplete Windows Updates particularly on Windows 7/8 systems where KB2999226 update (which installs UCRT) failed to install or was blocked by Windows Update errors leaving systems without UCRT support (8%), malware or virus infections that deleted, replaced, or corrupted system DLL files including UCRT components as part of malicious payload or system damage (4%), and manual DLL deletion by users who mistakenly removed files from System32 folder thinking they were unnecessary or following bad advice from unreliable "PC optimization" guides (2%). This comprehensive guide provides 6 proven methods to fix api-ms-win-crt-runtime-l1-1-0.dll error: installing Visual C++ Redistributable packages (both x86 and x64), running Windows Update to install KB2999226, using System File Checker and DISM to repair system files, manually registering DLL files, performing clean Visual C++ reinstallation, and updating Windows to latest version—ensuring you can launch applications without DLL errors, restore missing UCRT components, eliminate "program can't start" messages, and maintain stable application compatibility.

Method 1: Install Visual C++ Redistributable 2015-2022 (Primary Fix)

Missing Visual C++ Redistributable causes DLL error. Installing both x86 and x64 versions restores UCRT.

Installing Visual C++ Redistributable packages
  1. Download Visual C++ Redistributable (x64 version):
  2. Go to: aka.ms/vs/17/release/vc_redist.x64.exe
  3. Or search: "Visual C++ Redistributable latest supported downloads"
  4. Microsoft official download page appears
  5. Find: Visual Studio 2015, 2017, 2019, and 2022 section
  6. Download: vc_redist.x64.exe (64-bit version)
  7. File size: ~25 MB
  8. Install x64 Version:
  9. Right-click vc_redist.x64.exe → Run as administrator
  10. Accept license agreement
  11. Click Install
  12. Installation takes 1-3 minutes
  13. "Setup Successful" message appears
  14. Click Close
  15. Download Visual C++ Redistributable (x86 version):
  16. Go to same Microsoft page
  17. Download: vc_redist.x86.exe (32-bit version)
  18. File size: ~13 MB
  19. Install x86 Version:
  20. Right-click vc_redist.x86.exe → Run as administrator
  21. Accept license agreement
  22. Click Install
  23. Installation completes
  24. Click Close
  25. Why Both Versions Needed:
    • x64 (64-bit): For 64-bit applications
    • x86 (32-bit): For 32-bit applications running on 64-bit Windows
    • Many systems run both types of applications
    • Installing only one version may not fix all errors
  26. Restart Computer:
  27. Restart to complete installation
  28. DLL files registered with Windows
  29. Try launching application
  30. Error should be resolved

Method 2: Install Windows Update KB2999226 (Windows 7/8)

Windows 7/8 need specific update for UCRT. KB2999226 installs Universal C Runtime.

Installing KB2999226 update
  1. Check Windows Version:
  2. Press Windows + R, type winver, press Enter
  3. Shows Windows version
  4. This method for: Windows 7, Windows 8, Windows 8.1
  5. Windows 10/11: Skip this method (UCRT built-in)
  6. Download KB2999226 for Your System:
  7. Go to: Microsoft Update Catalog (catalog.update.microsoft.com)
  8. Search: KB2999226
  9. Find version matching your Windows:
    • Windows 7 x64: "Update for Windows 7 for x64-based Systems (KB2999226)"
    • Windows 7 x86: "Update for Windows 7 (KB2999226)"
    • Windows 8.1 x64: "Update for Windows 8.1 for x64-based Systems (KB2999226)"
    • Windows 8.1 x86: "Update for Windows 8.1 (KB2999226)"
  10. Click Download
  11. Save .msu file
  12. Install Update:
  13. Double-click downloaded .msu file
  14. Windows Update Standalone Installer opens
  15. Click Yes to install
  16. Installation takes 3-10 minutes
  17. "Installation complete" message
  18. Restart Computer:
  19. Restart required to complete update
  20. After restart: UCRT installed
  21. Try launching application
  22. Alternative - Windows Update:
  23. If download fails, try Windows Update:
  24. Control Panel → Windows Update
  25. Click Check for updates
  26. KB2999226 should appear in optional updates
  27. Select and install

Method 3: Run System File Checker and DISM

Corrupted system files cause DLL errors. SFC and DISM repair Windows components.

Repairing system files with SFC and DISM
  1. Open Command Prompt as Administrator
  2. Run DISM to Repair Component Store:
    DISM /Online /Cleanup-Image /RestoreHealth
  3. Takes 15-45 minutes
  4. Downloads good files from Windows Update
  5. Repairs Windows Component Store (WinSxS)
  6. Shows progress: 20%...40%...60%...100%
  7. "The restore operation completed successfully"
  8. Run System File Checker:
    sfc /scannow
  9. Takes 15-30 minutes
  10. Scans all Windows system files
  11. Replaces corrupted DLL files
  12. Shows: "Windows Resource Protection found corrupt files and successfully repaired them"
  13. Check SFC Results:
  14. SFC creates log file
  15. View detailed log:
    findstr /c:"[SR]" %windir%\Logs\CBS\CBS.log > "%userprofile%\Desktop\sfcdetails.txt"
  16. Creates sfcdetails.txt on Desktop
  17. Shows which files were repaired
  18. If SFC Cannot Fix Some Files:
  19. Run DISM again:
    DISM /Online /Cleanup-Image /RestoreHealth
  20. Then run SFC again:
    sfc /scannow
  21. Second pass often fixes remaining issues
  22. Restart computer
  23. Try launching application

Method 4: Manually Register DLL Files

Unregistered DLL causes error even if file exists. Registering makes Windows recognize it.

Registering DLL files manually
  1. Open Command Prompt as Administrator
  2. Register 64-bit DLL (on 64-bit Windows):
    regsvr32 C:\Windows\System32\ucrtbase.dll
  3. Message: "DllRegisterServer in ucrtbase.dll succeeded"
  4. Register 32-bit DLL (on 64-bit Windows):
    regsvr32 C:\Windows\SysWOW64\ucrtbase.dll
  5. Success message appears
  6. On 32-bit Windows:
  7. Only register System32 version:
    regsvr32 C:\Windows\System32\ucrtbase.dll
  8. Register API Set DLL:
    regsvr32 C:\Windows\System32\api-ms-win-crt-runtime-l1-1-0.dll
  9. If "Module failed to load" Error:
  10. DLL file actually missing (not just unregistered)
  11. Go back to Method 1 (install Visual C++ Redistributable)
  12. Or Method 3 (SFC/DISM to restore file)
  13. Restart Computer:
  14. Restart to complete registration
  15. Try launching application

Method 5: Perform Clean Visual C++ Reinstallation

Corrupted Visual C++ installation persists. Clean reinstall ensures fresh components.

Clean reinstalling Visual C++ Redistributables
  1. Uninstall Existing Visual C++ Redistributables:
  2. Settings → Apps → Apps & features
  3. Or: Control Panel → Programs and Features
  4. Find ALL entries starting with:
    • "Microsoft Visual C++ 2015 Redistributable"
    • "Microsoft Visual C++ 2017 Redistributable"
    • "Microsoft Visual C++ 2019 Redistributable"
    • "Microsoft Visual C++ 2022 Redistributable"
    • "Microsoft Visual C++ 2015-2022 Redistributable"
  5. Uninstall Both x86 and x64 Versions:
  6. For each entry:
    • Click → Uninstall
    • Follow uninstaller
    • Takes 1-2 minutes per package
  7. Note on Older Versions:
  8. Keep these if present (don't uninstall):
    • Visual C++ 2005
    • Visual C++ 2008
    • Visual C++ 2010
    • Visual C++ 2012
    • Visual C++ 2013
  9. Only uninstall 2015-2022 versions
  10. Clean Temporary Files:
  11. Press Windows + R, type %temp%, press Enter
  12. Delete all files in Temp folder
  13. Some files may be in use (skip them)
  14. Restart Computer:
  15. Restart before reinstalling
  16. Clears any locked files
  17. Reinstall Visual C++ Redistributables:
  18. Download latest versions (Method 1)
  19. Install x64 version first
  20. Then install x86 version
  21. Restart computer
  22. Try launching application

Method 6: Update Windows to Latest Version

Outdated Windows lacks UCRT updates. Latest updates include all runtime components.

Updating Windows to latest version
  1. Open Windows Update:
  2. Windows 10/11: Settings → Update & Security → Windows Update
  3. Windows 8/8.1: PC Settings → Update and recovery → Windows Update
  4. Windows 7: Control Panel → Windows Update
  5. Check for Updates:
  6. Click Check for updates
  7. Windows searches for available updates
  8. Takes 2-10 minutes
  9. Install All Available Updates:
  10. Install:
    • Quality Updates (cumulative updates)
    • Security Updates
    • Optional Updates (if any)
  11. Click Download and install
  12. Takes 30 minutes - 2 hours depending on update size
  13. Restart Computer:
  14. Restart when prompted
  15. Updates install during restart
  16. May take 10-30 minutes
  17. "Working on updates" screen appears
  18. Repeat Until Fully Updated:
  19. After restart: Check for updates again
  20. Some updates require multiple passes
  21. Repeat until "You're up to date" message
  22. For Windows 7 Users:
  23. Ensure KB2999226 installed (Method 2)
  24. Also install: Service Pack 1 (if not already)
  25. Windows 7 mainstream support ended, but updates still available
  26. Try launching application

💡 Pro Tip: Prevent Future DLL Errors

Never manually delete DLL files from System32 or SysWOW64: These folders contain critical Windows components—deleting files causes application failures and system instability. Install Visual C++ Redistributables when prompted: Many application installers include redistributables—don't skip these components during installation. Keep Windows fully updated: Windows Update delivers runtime library updates and security patches—check monthly for updates. Don't use "DLL download sites": Websites offering individual DLL downloads often distribute malware or outdated files—always get DLLs from official Microsoft redistributables. Install both x86 and x64 Visual C++ packages: Even on 64-bit Windows, many applications are 32-bit—need both versions for full compatibility. Before uninstalling Visual C++ Redistributables: Don't remove them to "free space"—they're tiny (50-100 MB total) but required by hundreds of applications. Use Windows Defender: Malware often corrupts or deletes system DLLs—keep antivirus active and updated. For developers: When distributing applications, include Visual C++ Redistributable installer or use static linking to avoid dependency issues. Backup before major changes: Before uninstalling software or making system changes, create System Restore point—allows rollback if DLL issues occur. For gamers: Many games require Visual C++ 2015-2022—install before gaming to avoid launch failures.

Frequently Asked Questions

Q: I installed Visual C++ Redistributable but still get the DLL error. What's wrong?

A: Several possible causes if error persists after installation: (1) Didn't install both x86 and x64 versions: Most common mistake—users install only x64 thinking it covers both. 32-bit applications need x86 version even on 64-bit Windows. Solution: Install BOTH vc_redist.x86.exe AND vc_redist.x64.exe. (2) Didn't restart computer: DLL registration requires restart to take effect. Restart after installing redistributables. (3) Windows system files corrupted: Even with redistributables installed, corrupted Windows prevents proper DLL loading. Run SFC and DISM (Method 3) to repair system files. (4) Antivirus blocking DLL registration: Some aggressive antivirus programs block DLL registration during installation. Temporarily disable antivirus, reinstall redistributables, restart, re-enable antivirus. (5) Installed wrong version: Ensure downloading from official Microsoft site (aka.ms/vs/17/release/)—third-party downloads may be outdated or corrupted. (6) Application requires older Visual C++ versions: Some applications need Visual C++ 2013 or earlier. Check application documentation, install required version. (7) Deep system corruption: If nothing works, perform Windows Repair Install (keeps files/apps but repairs Windows)—last resort before clean install.

Q: Can I just download the DLL file from a "DLL download website" instead of installing the full redistributable?

A: Strongly NOT recommended—dangerous and ineffective. (1) Security risks: DLL download websites often bundle malware, trojans, or viruses with DLL files—infecting system when you copy DLL. No quality control on these sites. (2) Wrong DLL version: api-ms-win-crt-runtime-l1-1-0.dll has multiple versions for different Windows versions and architectures—downloading wrong version causes more errors or system instability. (3) Missing dependencies: This DLL is part of UCRT which includes 50+ interconnected DLL files—downloading one file doesn't install complete runtime, other applications will fail with different DLL errors. (4) No proper registration: Simply copying DLL to System32 doesn't register it with Windows—applications still can't find it. Redistributable installer properly registers all components. (5) Violates Microsoft licensing: Redistributing individual system DLLs outside official packages violates Microsoft's terms. (6) Proper solution: Install official Visual C++ Redistributable from Microsoft (Method 1)—free, safe, includes all dependencies, properly registers components, takes 5 minutes. Bottom line: DLL download sites are scams preying on desperate users—never use them. Always use official Microsoft redistributables.

Q: Why does this error only appear for some applications but not others?

A: Different applications compiled with different Visual Studio versions have different dependencies. (1) Compiler version matters: Applications compiled with Visual Studio 2015 or later require UCRT (api-ms-win-crt-runtime-l1-1-0.dll). Applications compiled with older Visual Studio (2013, 2012, 2010) use older runtime libraries (msvcr120.dll, msvcr110.dll, msvcr100.dll)—don't need UCRT. (2) Static vs dynamic linking: Some applications use "static linking"—include runtime library code directly in .exe file, no external DLL needed. Others use "dynamic linking"—rely on system-installed DLLs. Statically-linked apps never show DLL errors. (3) Application age: Older applications (pre-2015) don't use UCRT—won't show this error. Newer applications (2015+) require UCRT—show error if missing. (4) 32-bit vs 64-bit: If you installed only x64 redistributable, 64-bit apps work but 32-bit apps show error (or vice versa). Need both versions for full compatibility. (5) Why this matters: Error appearing for one application indicates system-wide issue—other modern applications will also fail. Fix affects all applications, not just one. (6) Testing: After fixing, test multiple applications—ensures complete fix, not just workaround for one app.

Q: I'm on Windows 7 and can't install KB2999226. Windows Update says it's not applicable. How to fix?

A: KB2999226 has prerequisites on Windows 7—must install Service Pack 1 and other updates first. (1) Install Windows 7 Service Pack 1 (SP1): KB2999226 requires SP1. Check if installed: Right-click Computer → Properties → shows "Service Pack 1" if installed. If not: Download SP1 from Microsoft, install, restart. (2) Install prerequisite updates: After SP1, install these in order: (a) KB2533623 (Microsoft Security Advisory update), (b) KB2670838 (Platform Update), (c) KB3033929 (SHA-2 code signing support). Download from Microsoft Update Catalog, install each, restart. (3) Then install KB2999226: After prerequisites, KB2999226 will install successfully. (4) Alternative—Install Visual C++ Redistributable directly: Even without KB2999226, installing Visual C++ Redistributable 2015-2022 (Method 1) often works—redistributable includes UCRT components. Try this first before hunting down prerequisite updates. (5) Windows 7 Extended Support ended: Microsoft no longer provides mainstream updates for Windows 7 (ended January 2020). Consider upgrading to Windows 10/11 for continued support and compatibility. (6) If all fails: Use Windows 7 Update Convenience Rollup (KB3125574)—mega-update including most patches from 2011-2016, includes UCRT prerequisites. Download from Microsoft, install (takes 1-2 hours), restart.

Q: After fixing the DLL error, other applications now show different DLL errors (like ucrtbase.dll or vcruntime140.dll). Why?

A: Indicates incomplete Visual C++ Redistributable installation or partial system corruption. (1) UCRT is a package of DLLs: Universal C Runtime includes multiple DLL files: api-ms-win-crt-runtime-l1-1-0.dll (the one you fixed), ucrtbase.dll (base runtime), vcruntime140.dll (Visual C++ runtime), and 50+ other api-ms-win-crt-*.dll files. All must be present for applications to work. (2) Why new errors appear: Different applications use different functions from UCRT—each function in a different DLL. First application used functions in api-ms-win-crt-runtime-l1-1-0.dll (now fixed), second application uses functions in ucrtbase.dll (still missing). (3) Solution—Complete Visual C++ reinstallation: Perform Method 5 (Clean Reinstallation)—uninstall all Visual C++ 2015-2022 packages, restart, reinstall both x86 and x64 versions. Ensures complete UCRT installation. (4) Also run SFC/DISM: Multiple DLL errors suggest system file corruption. Run Method 3 (SFC and DISM) to repair all Windows components at once. (5) Check disk health: Recurring DLL corruption may indicate failing hard drive. Run CHKDSK: chkdsk C: /f /r—repairs disk errors. Use CrystalDiskInfo to check drive SMART status. (6) Prevention: After complete fix, create System Restore point—allows quick recovery if DLL issues recur.