Fix the Side-by-side Configuration Error on Windows

A Side-by-side configuration error means Windows could not create the activation context an application needs. The failure can involve a Visual C++ assembly, an x86/x64 mismatch, an application manifest, or damaged Windows components. Start by isolating whether one app or several apps fail, then use sxstrace.exe to identify the exact assembly before repairing a runtime. This guide provides four repair paths, from targeted application repair to broader Windows repair.

Symptoms

Windows may display The application has failed to start because its side-by-side configuration is incorrect . The message can also direct you to the application event log or sxstrace.exe .

• One named application fails immediately while other programs work.
• A program fails after an update, interrupted setup, or migration to a new PC.
• Multiple unrelated programs or Windows features fail, suggesting a wider system-component issue.

What Causes a Side-by-side Configuration Error?

• A required Visual C++ runtime or assembly is missing: the application cannot locate the assembly it declares.
• An x86/x64 architecture mismatch: a 32-bit dependency and a 64-bit dependency are different requirements.
• An application manifest or assembly-version conflict: the declared assembly identity does not match an installed component.
• A damaged application installation: the program’s files or manifest may be incomplete or inconsistent.
• Windows component corruption: this is more likely when several applications or Windows features show related failures.

Quick Diagnosis Checklist

• Only one application fails: begin with Method 1 to restore that application’s installation.
• The message references sxstrace.exe , or reinstalling did not help: use Method 2 to identify the assembly, version, and architecture before installing anything.
• The trace identifies a Microsoft VC assembly: use the named runtime generation and architecture to repair the matching Visual C++ Redistributable; do not install every package.
• Several programs or Windows components fail: use Method 3 to repair the Windows image and protected system files.
• Launch failures accompany detected DLL or runtime issues: Method 4 is a separate guided scan, repair, and recheck workflow.

Quick Method Comparison

Method 1: Reinstall the affected application

When to Use

Use this first when just one application fails, especially after an update or interrupted installation. A fresh official installer can restore the app’s manifest and bundled components.

Step-by-Step Guide

1. Close the affected application and its installer.
2. Uninstall the application from Windows Settings.
   
3. Restart Windows.
4. Install a fresh copy from the application developer’s official source.
5. Launch the application after setup completes.

How to Verify

The application opens to its normal first screen. If the same error returns, capture a trace instead of repeatedly installing unrelated runtimes.

Method 2: Capture and read an SxS trace

When to Use

Use this method when the error names sxstrace.exe or Method 1 did not work. The trace records activation-context events and identifies the dependency to repair.

Step-by-Step Guide

1. Open Command Prompt as an administrator.
   
2. Start tracing.

   sxstrace trace -logfile:%TEMP%\sxstrace.etl
         

3. Launch the failing application and reproduce the error once.
4. Return to Command Prompt and press Enter to stop tracing.
5. Parse the trace into text.

   sxstrace parse -logfile:%TEMP%\sxstrace.etl -outfile:%TEMP%\sxstrace.txt
         

6. Open %TEMP%\sxstrace.txt and note the assembly name, version, and processorArchitecture .

How to Read SxS Trace Results

How to Verify

The text file contains details from the reproduced failure. Apply only the repair indicated by its assembly generation and architecture, then relaunch the app. Send the relevant excerpt to the developer if the trace points to the app’s own manifest.

Method 3: Repair Windows system files with DISM and SFC

When to Use

Use this method when multiple unrelated applications fail or Windows features also malfunction. Run DISM first so Windows can repair the component store used by System File Checker.

Step-by-Step Guide

1. Open Command Prompt as an administrator.
2. Run DISM.

   DISM.exe /Online /Cleanup-image /Restorehealth
         

3. Wait for DISM to report completion.
4. Run System File Checker.

   sfc /scannow
         

   
5. Keep Command Prompt open until verification reaches 100%.
6. Restart Windows and test the affected application.

How to Verify

Review both command results, restart, and open the affected application. If one application still fails, return to Method 2 for app-specific evidence.

Method 4: Diagnose and Fix DLL and System Issues with Fionn DLL Fixer

When to Use

Use this recommended workflow when launch failures coincide with DLL, runtime, or system issues that need a guided scan. Fionn DLL Fixer scans detected DLL and system issues, then supports repair and recheck. It does not replace an SxS trace when you need the exact application manifest diagnosis.

Step-by-Step Guide

1. Launch Fionn DLL Fixer. The software automatically scans your PC for DLL and system issues and displays the detected results when the scan is complete.
2. After the scan finishes, click “Repair” to start fixing all detected DLL and system issues automatically.
3. Wait while the repair is in progress. During this process, the button changes to “Fixing” until all issues have been repaired.
4. When the repair is complete, click “Ok” in the confirmation dialog. If prompted, restart your computer before checking whether the problem has been resolved.
5. If the issue still persists after restarting, click “Recheck” to perform another scan. If new issues are found, click “Repair” again to fix them.

How to Verify

Confirm the recheck results, then launch the application twice. If the Side-by-side configuration error remains, save an SxS trace and share the assembly details with the application developer.

Verification Checklist

• The application opens twice in succession without the configuration error.
• The application reaches the screen where it previously failed.
• The repaired Visual C++ component matches the trace’s generation and architecture.
• Other affected applications also start normally.
• sxstrace.txt is available for official support if the error returns.
• DISM and SFC completed before judging a system-wide repair.

Conclusion

For one failing program, reinstall the application first. If it still fails, use SxSTrace to determine the actual assembly, Visual C++ generation, and x86 or x64 requirement; that evidence is more useful than installing every redistributable. Use DISM and SFC when the issue affects several programs or Windows components. For detected DLL and system issues, Fionn DLL Fixer provides a scan, repair, and recheck route. Verify the result by restarting when needed and opening the app twice. If the error persists, provide the trace excerpt to the developer or official support.

FAQ

What does a Side-by-side configuration error mean?

Windows could not build the application’s activation context from the assemblies and manifests it requires. The error can involve a runtime, architecture, version, or application-installation issue.

Should I install every Visual C++ package?

No. Use the SxS trace to identify the Visual C++ assembly generation and architecture, then repair only the matching component or reinstall the affected app.

Why can a 32-bit application fail on 64-bit Windows?

A 32-bit application can require an x86 assembly. A 64-bit edition of the runtime does not replace that separate x86 dependency.

Will DISM and SFC fix an application-specific error?

They can repair Windows components and protected system files, but they do not replace an application’s manifest or identify its exact dependency. Use an SxS trace for a single-app failure.

Where are the SxS trace files saved?

With the commands in this guide, the files are saved in the current user’s temporary folder: %TEMP%\sxstrace.etl and %TEMP%\sxstrace.txt .