“Build failed” on Database First Scaffold-DbContext

Question

I\'m trying to generate classes from a database (EntityFramework\'s database first approach).

For convenience, I\'m more or less walking along with this tutorial: ht

Answer 1

1. Make sure your project is not running
2. Make sure your project is compiling

That worked for me.

Answer 2

I know this is old, but I spent a while trying to figure this out today, so I hope this helps someone.

I have a .Net Core project but I want to scaffold my files into a .Net Standard class library. DbContext-Scaffold in the package manager console didn't work for me, but dotnet ef dbcontext scaffold in a regular command prompt did.

I had to install these packages in my class library:

• Microsoft.EntityFrameworkCore.SqlServer
• Microsoft.EntityFrameworkCore.Design
• Microsoft.EntityFrameworkCore.Tools

I had to have a .Net Core project set as the startup project in my solution and that project had to have a reference to my class library. I think that last part is what I was missing that kept me scratching my head for so long.

Finally, I cd'd into the class library from a command prompt and ran this:

dotnet ef dbcontext scaffold "<connection string>" Microsoft.EntityFrameworkCore.SqlServer -o <output folder> -s <relative path to my startup project>

Answer 3

I resolved it with right click on projects and "Unload Project" let only the EF project and run the commands

Answer 4

For me the issue was that I was trying to set it up in a new blank console project inside of the solution, which had no files, so the scaffolding tried to use this project as a startup project and couldn't find Main. I fixed it by adding a new file with an empty main

Answer 5

I still had this problem even when I ensured that my project (which had EF Core installed) built correctly. It still failed with the "Build failed." message, which is visible when using the -Verbsose flag.

I had to do this in my case:

• Create a throw-away ASP.NET Core web application solution
• Add the EF Core NuGet package to the solution
• Add the EF Core Sql Server provider NuGet package (because I'm using SqlServer)
• Add the EF Core Tools NuGet package
• Switch -Project in the package manager console command to point to my newly-created (and EF Core-provisioned) project. The last step was just for good measure, since there was only one project in my throw-away solution.

It seems that this whole process requires an ASP.NET core project (or just a .NET Core project that isn't a class library) somewhere in the solution, presumably set as the solution startup project too.

Answer 6

I resolved it by stopping my server and then running it again.