Software⏱️ 2 min read📅 2026-05-31

How to Fix: Visual Studio 2017 error: Unable to start program, An operation is not legal in the current state

Error occurs after fresh installation of Visual Studio 2017 and .NET Core Web project.

Quick Answer: Check if the .NET Core SDK is properly installed and configured, and ensure that the correct version of the SDK is used for the project.

📋 Table of Contents

  1. 🔍 Why This Happens
  2. 🔧 Proven Troubleshooting Steps
  3. 💡 Conclusion

After a fresh installation of Visual Studio 2017, you may encounter the error 'Unable to start program, An operation is not legal in the current state' when trying to run your .NET Core Web project. This issue can be frustrating, but don't worry – we've got you covered!

🔍 Why This Happens

  • One common cause of this error is the incorrect configuration of the Visual Studio 2017 IDE. When you first install .NET Core, it may not be properly integrated with Visual Studio.

🔧 Proven Troubleshooting Steps

Method 1: Check and Correct IDE Configuration

  1. Step 1: Open Visual Studio 2017 and go to Tools > Options.

Method 2: Update .NET Core SDK

  1. Step 1: Open a terminal and run the command `dotnet tool install --global dotnet-sdk` to update your .NET Core SDK.

💡 Conclusion

By following these steps, you should be able to resolve the 'Unable to start program' error in Visual Studio 2017 and get your .NET Core Web project running smoothly on Chrome.

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