Скачать или смотреть Resolving the No design-time services were found Error with EF Scaffold-DbContext in .NET 6.0

Discover how to troubleshoot the `NullReferenceException` when using EF Scaffold-DbContext with .NET 6.0, and learn about the solutions available.
---
This video is based on the question https://stackoverflow.com/q/69036107/ asked by the user 'CNHume' ( https://stackoverflow.com/u/4552096/ ) and on the answer https://stackoverflow.com/a/70160305/ provided by the user 'CNHume' ( https://stackoverflow.com/u/4552096/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: Why does the EF Scaffold-DbContext command throw an NRE, after reporting 'No design-time services were found.', when targeting net6.0?

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
Troubleshooting the EF Scaffold-DbContext Command in .NET 6.0

If you're a developer working with Entity Framework (EF) in .NET 6.0, you may have encountered an unexpected hurdle: the Scaffold-DbContext command throws a NullReferenceException (NRE) after reporting that "No design-time services were found." This can be frustrating, especially when you're trying to leverage new features or improve your application’s performance. In this guide, we’ll explore the issue in detail and provide you with actionable solutions to get past this error.

Understanding the Problem

What Happened?

When you attempt to run the Scaffold-DbContext command in a .NET 6.0 environment, specifically using the command below:

[[See Video to Reveal this Text or Code Snippet]]

you might find yourself facing a message like this:

[[See Video to Reveal this Text or Code Snippet]]

This error message indicates that something went wrong during the process of scaffolding your database context. It’s a common issue for developers working with the preview version of .NET SDKs, particularly when new features are introduced.

Symptoms of the Issue

NRE Occurs: Throws a NullReferenceException while trying to resolve connection strings.

No Progress: You cannot scaffold your context until the issue is resolved, affecting your development workflow.

Retargeting Needed: You've mentioned having to roll back to a previous version (net5.0) to get the command working, which isn't an ideal solution.

The Solution

Recent Updates from Microsoft

Fortunately, the issue has been addressed in a more recent update from Microsoft:

Visual Studio Release: As of the release of Visual Studio 2022, Version 17.1.0 Preview 1.1, things have improved significantly.

Dotnet-ef Upgrade: Upgrades, especially to dotnet-ef Version 6.0.0, resolve these issues and allow the Scaffold-DbContext command to execute correctly once again with Named Connection Strings targeting .NET 6.0.

Steps to Resolve the Issue

To resolve the No design-time services were found error and get your Scaffold-DbContext command working smoothly, follow these steps:

Update Visual Studio: Ensure you have the latest version of Visual Studio installed. Check for updates regularly, as new preview and stable versions frequently include fixes for common issues.

Upgrade Dotnet-ef Tools: Make sure that you are using the latest version of the dotnet-ef Tool:

[[See Video to Reveal this Text or Code Snippet]]

Check .NET SDK Versions: Ensure that your project file is targeting a stable version of .NET 6.0 or the latest release candidate. Adjust if necessary.

Test the Command Again: Once you have performed updates, re-run the Scaffold-DbContext command. It should now complete successfully without throwing an NRE.

Consult Documentation: Keep an eye on the official Entity Framework Core documentation and their GitHub repository for any upcoming fixes and features related to the .NET SDK.

Conclusion

The No design-time services were found error, accompanied by a NullReferenceException, can be disheartening for developers working within the EF ecosystem on .NET 6.0. Thankfully, through Microsoft's updates, the command has been restored to full functionality. By ensuring your tools and SDK versions are up to date, you're setting yourself up for success in your development pursuits.

Should you face any challenges continuing with your EF migrations or setups, don't hesitate to reach out to the community or consult the official documentation. Happy coding!