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10 Tech How-To

Fix Side-by-Side Error 59 on Windows 10

Guide 10-22538 · Updated · Step by step

Side-by-side error 59 on Windows 10 occurs when the Visual C++ runtime libraries are missing or corrupted, and the fix is to reinstall the correct Microsoft Visual C++ Redistributable packages. This error typically appears when launching an application, with a message like “The application has failed to start because its side-by-side configuration is incorrect.” Below are the exact steps to resolve it, plus background on why it happens.

What Causes Side-by-Side Error 59?

Windows uses a feature called Side-by-Side (SxS) assembly to manage DLL versions. Applications declare which versions of runtime libraries they need, and Windows loads them from the WinSxS folder. Error 59 specifically means ERROR_SXS_ASSEMBLY_NOT_FOUND – the required assembly (usually a Visual C++ runtime) is not present or is damaged.

Common triggers include:

  • Uninstalling or updating a Visual C++ Redistributable package.
  • Installing a new program that overwrites an older runtime.
  • Corrupted system files after a crash or power outage.
  • Windows Update partially installing a .NET or VC++ update.

Step-by-Step Fix for Error 59

  1. Identify the missing runtime. Open Event Viewer (press Win+R, type eventvwr). Under Windows Logs > Application, look for an Error event with source SideBySide. The event details list the missing assembly name and version, e.g., Microsoft.VC90.CRT.
  2. Download the correct Visual C++ Redistributable. Go to Microsoft’s official download page (search “Visual C++ Redistributable latest supported downloads”). Install both the x86 and x64 versions, even if you use 64-bit Windows, because many 32-bit apps need the x86 runtime.
  3. Install the runtime as administrator. Right-click the downloaded vc_redist.x86.exe or vc_redist.x64.exe and select Run as administrator. Follow the prompts and restart your PC.
  4. If the error persists, repair the runtime. Open Settings > Apps > Apps & features, find the Visual C++ Redistributable entries, select one, click Modify, then choose Repair. Do this for each installed version.
  5. Run System File Checker. Open Command Prompt as administrator (Win+X > Command Prompt (Admin)) and run sfc /scannow. This repairs corrupted Windows files that may affect the SxS store.
  6. Reinstall the failing application. If the error is tied to one program, uninstall it, restart, and reinstall. This forces the app to re-register its dependencies.

What If the Error Still Appears?

If you’ve reinstalled the runtimes and the error remains, the problem may be a corrupted WinSxS store. You can use the DISM tool to repair it:

  1. Open Command Prompt as administrator.
  2. Run DISM /Online /Cleanup-Image /RestoreHealth and wait for completion.
  3. Reboot and run sfc /scannow again.

Another possibility is that the application itself is outdated and requires an older runtime (like VC++ 2005 or 2008). Check the program’s documentation or support forum for which specific runtime it needs. You can install multiple versions side-by-side; they do not conflict.

How to Avoid Future Occurrences

  • Always install Visual C++ Redistributables from Microsoft’s official site, not third-party download sites.
  • Keep Windows Update enabled – it often patches runtime issues.
  • When uninstalling software, use the official uninstaller and avoid manually deleting DLL files.
  • If you use a PC repair tool, avoid ones that “clean” the WinSxS folder; this can break side-by-side assemblies.

Common Misconceptions

Many users think error 59 is caused by a virus or a missing .NET Framework. While malware can corrupt files, the error is almost always a runtime library issue. .NET Framework is separate from Visual C++ runtimes, though some apps need both. Also, error 59 is not the same as error 0xc000007b (which is a 32-bit/64-bit mismatch) – though the fixes overlap.

Frequently Asked Questions

Can I just copy a missing DLL into the System32 folder?

No. Copying a DLL manually rarely works because the SxS store requires a manifest and catalog files. It’s better to install the entire redistributable package, which registers everything correctly.

Why does error 59 happen after a Windows update?

Windows Update sometimes replaces or removes older runtime files. If a new update conflicts with an app’s declared dependency, the app fails to start. Reinstalling the runtime usually resolves it.

Do I need both x86 and x64 runtimes?

Yes, on 64-bit Windows. Many 32-bit applications require the x86 runtime, and 64-bit apps need the x64 version. Installing both covers all cases.

Will this fix work on Windows 11?

Yes, the same steps apply to Windows 11, as the SxS architecture and Visual C++ runtimes are unchanged.

Is there a way to see which runtime a specific app needs?

You can use the Event Viewer details as mentioned, or use a tool like Dependencies (a free utility) to inspect the app’s manifest. However, the simplest approach is to install all available VC++ redistributables.

Related

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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