How to Debug Unhandled Exception: System.Runtime.InteropServices.SEHException in Visual Studio

This comprehensive guide provides effective methods to troubleshoot and resolve the `Unhandled Exception` error in Visual Studio, ensuring smooth development of your .NET applications.
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Diagnosing Unhandled Exceptions in Visual Studio

Developers often encounter errors during coding that can severely hinder progress, especially when dealing with components like Visual Studio and .NET. One particularly daunting issue is the Unhandled Exception: System.Runtime.InteropServices.SEHException: External component has thrown an exception error that appears during the build process. If you're facing similar issues in Visual Studio when using the Debug target button but find success with the .NET CLI, you may feel stuck and overwhelmed.

This guide aims to guide you through the troubleshooting process for this error, helping you to understand the root causes and the steps you can take to resolve them.

Understanding the Problem

When attempting to build a .NET application using Visual Studio, you might see error messages related to the System.Runtime.InteropServices.SEHException. This indicates that an external component has thrown an exception—often tied to issues in the Common Language Runtime (CLR), your project configuration, or possibly your machine environment.

Common Signs of This Error:

Build errors in Visual Studio.

Successful compilation and execution via the .NET CLI.

Iteration of similar error messages that reference files in the Roslyn compiler and CLR.

Steps to Debug the SEHException Error

Here are some systematic ways to approach resolving the Unhandled Exception error in Visual Studio:

1. Repair Visual Studio Installation

Sometimes, the configuration or installed components of Visual Studio may become corrupted. Running a repair can often resolve hidden issues:

Open Visual Studio Installer.

Select your version of Visual Studio.

Click on Modify, then Repair.

2. Reinstall Visual Studio

If repairing does not work, a complete reinstallation may be necessary:

Uninstall Visual Studio from Control Panel.

Download the latest version from the Visual Studio website and reinstall it.

3. Check for File Accessibility

The error messages may indicate issues with specific files or directories. Make sure:

You have permission to access .dll files mentioned in the error logs.

The disk or path is still valid (i.e., not on a removable device).

4. Assess Windows Environment

The errors may stem from underlying OS issues. Steps include:

Running CHKDSK to check your disk integrity:

Open Command Prompt and type CHKDSK /F, then press Enter.

Verifying that all necessary Windows updates are applied.

5. Examine Event Viewer

The Windows Event Viewer tool can provide more context on errors:

Press Windows + R to open the Run dialog, type eventvwr, and press Enter.

Look under Windows Logs Application to find related error entries.

6. Create a Fresh Project

If the error persists, test it by creating a new project:

Use the template to create a new ASP.NET Core Web app.

Check if the problem continues; if error-free, it may point to a project-specific setting.

7. System Restoration

In some severe cases, a reinstallation of the operating system may be the last solution:

Ensure to back up all important data.

Following the reinstallation, set up your development environment from scratch.

8. Document and Analyze Dependencies

Sometimes, other installed extensions or dependencies may conflict with the build process:

Listing out dependencies and ensuring they are up to date may help resolve unexpected components throwing exceptions.

Final Thoughts

Encountering an Unhandled Exception: System.Runtime.InteropServices.SEHException error can be frustrating, especially when your project compiles successfully via the command line. Ho