"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: https://docs.efproject.net/en/latest/platforms/full-dotnet/existing-db.html

I'm at a point where I am running the equivalent of this line of code in the Visual Studio Package Manager Console:

Scaffold-DbContext "Server=(localdb)\mssqllocaldb;Database=Blogging;Trusted_Connection=True;" Microsoft.EntityFrameworkCore.SqlServer -Verbose

This line of code is generating the error (with -Verbose mode on):

Using startup project 'EFSandbox'.
Using project 'EntityFrameworkCore'
Build started...
Build failed.

I see no other options that produce any meaningful output, and I see no documentation on this particular error. If it helps at all, this project does not have a project.json file, currently. Everything is in the .csproj file, which I have not manually edited.

Do you get any errors/warnings when you recompile the whole solution? — Ignas
– Ignas, Commented Aug 15, 2016 at 18:57
@Ignas Did that, and yes, I got dependency errors that didn't exist before I recompiled, and that just shouldn't have existed. Rather than try to fight it, I remade the solution. I have a new problem now, though. Guess that I should make a new question after a bit (if this one is similar) as opposed to editing this one. — LightToTheEnd
– LightToTheEnd, Commented Aug 15, 2016 at 19:24
For me, what got it working was to make sure the entire solution ( not just the project) builds successfully before issuing the scaffold command. — manish gupta
– manish gupta, Commented Apr 2, 2018 at 17:04
dotnet ef dbcontext scaffold "(connectionstring)" Microsoft.EntityFrameworkCore.SqlServer --no-build — ValGe
– ValGe, Commented Aug 27, 2020 at 11:09

Simon_Weaver · Accepted Answer · 2020-07-09 07:46:06Z

255

Two most important tips:

[1] - Make sure that your project builds completely before you run a new scaffold command.

Otherwise...

You'll start writing a line of code.
You'll realize a required DB column is missing from your model.
You'll go to try to scaffold it.
Twenty minutes later you'll realize the reason your build (and scaffold command) is failing is because you literally have a half written line of code. Oops!

[2] - Check into source control or make a copy:

Allows you to easily verify what changed.
Allows rollback if needed.

You can get some very annoying 'chicken and egg' problems if you get unlucky or make a mistake.

For EF Core 2

Scaffold-DbContext -Connection "Server=(local);Database=DefenderRRCart;Integrated Security=True;Trusted_Connection=True;" -Provider Microsoft.EntityFrameworkCore.SqlServer -OutputDir RRStoreContext.Models -context RRStoreContext -Project RR.DataAccess -force

For EF Core 3

dotnet ef dbcontext scaffold "Server=tcp:XXXXX.database.windows.net,1433;Initial Catalog=DATABASE_NAME;Persist Security Info=False;User ID=USERNAME;Password=PASSWORD;MultipleActiveResultSets=False;Encrypt=True;TrustServerCertificate=False;Connection Timeout=30;" Microsoft.EntityFrameworkCore.SqlServer -o DB.Models --context-dir DB.Contexts --context RRDBContext --project RR.EF.csproj --force --use-database-names

Note: -force will overwrite files but not remove ones that don't exist any more. If you delete tables from your DB you must delete the old entity files yourself (just sort in Explorer by date and delete the old ones).

Full Scaffolding reference:

EF Core 2:

https://docs.efproject.net/en/latest/miscellaneous/cli/powershell.html#scaffold-dbcontext (this

EF Core 3:

https://learn.microsoft.com/en-us/ef/core/miscellaneous/cli/dotnet

edited Jul 9, 2020 at 7:46

answered Oct 29, 2016 at 18:23

Simon_Weaver

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20 Comments

sofsntp Over a year ago

what do you do if for instance you removed an entity file ? Scaffold won't work because you are missing this file but it won't scaffold because it doesn't build. Quite annoying.

Sam Over a year ago

Annoyingly you seem to need to be able to build the entire solution. I had errors in other projects but the project to scaffold was fine. Solution was to select the other projects and "unload" them. Then scaffold, then reload.

Seraphim's Over a year ago

--> Make sure that your project builds completely <-- Good!

Jean-Joseph Over a year ago

What do you know? The error was in another project. It's weird that the build failed error did not specify where the error occur until the entire solution is built.

aaaaaa Over a year ago

as usual, what an error message by microsoft. Can't wait to change jobs so I don't have to deal with microsoft's bs

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Mxaza · Accepted Answer · 2020-11-11 11:12:41Z

30

Manually building the project by pressing Ctrl+Shift+B helped me to see the errors that were causing the build to fail.

edited Nov 11, 2020 at 11:12

answered Jun 28, 2018 at 16:40

Mxaza

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3 Comments

Gert Arnold Over a year ago

As the accepted answer already said years before. "Make sure that your project builds completely before you run a new scaffold command."

Becca Over a year ago

This did not reveal the issue for me. Visual Studio kept building successfully, even after cleans. Adding the --verbose flag to dotnet ef scaffold did not help. I had to do a dotnet build to see the error.

Sanushi Salgado Over a year ago

Thanks a lot! Entering Ctrl + Shift + B displayed all my build errors in VS & saved my time.

melicent · Accepted Answer · 2018-09-07 18:43:24Z

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>

bcr · Accepted Answer · 2017-08-27 18:35:43Z

6

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.

edited Aug 27, 2017 at 18:35

answered Aug 27, 2017 at 15:35

bcr

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1 Comment

Regianni Over a year ago

This is probably one of the more useful entries on this page. The -verbose flag should push in the correct direction as it covers the multitude of things which can go wrong with scaffold.

Joel Balmer · Accepted Answer · 2019-07-15 16:14:39Z

6

Thanks to the above, rebuilding the project solution solved this. Some crucial caveats for me personally were:

Running the dotnet build was not enough (I had asssumed it was)!
In visual studio menu, Build > Build solution (Ctrl + Shift + B)
- I believe I was simply trying to run the dotnet build command while inside a child project (myProject.data)
- Rebuilding the parent project (myProject) solution was the key

I hope that helps someone else who was equally confused!

answered Jul 15, 2019 at 16:14

Joel Balmer

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Josh Siegl · Accepted Answer · 2018-12-18 16:24:36Z

5

Make sure your project isn't running, for some reason this command doesn't work while my API is running in the background.

answered Dec 18, 2018 at 16:24

Josh Siegl

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James Joyce · Accepted Answer · 2017-09-11 02:12:10Z

Using VS2017 Preview 3, .NET Core 2 (PREVIEW) I had all sorts of issues, but eventually I took the approach suggested above and created a brand new solution.

Created new .NET Core solution
Edited project file and changed 1.0 to 2.0: <TargetFramework>netcoreapp2.0</TargetFramework>
Closed/re-opened solution

Then, added the Entity Framework:

In PackageManager console:
- Install-package Microsoft.EntityFrameworkCore.SqlServer -Version 2.0.0-preview2-final
- Install-package Microsoft.EntityFrameworkCore.Tools -Version 2.0.0-preview2-final
- Install-package Microsoft.EntityFrameworkCore.Design -Version 2.0.0-preview2-final
Edited project file, and added: <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.Dotnet" Version="2.0.0-preview2-final" />

Then;

Opened the Powershell command prompt and changed directory into Scaffold project folder
Ran: dotnet ef dbcontext scaffold "Server=DESKTOP-MB70B7U; Database=ForexForme; Trusted_Connection=True" Microsoft.EntityFrameworkCore.SqlServer -o Models
- Where you put in your own connection string!
- Models is the name of my directory where I put all my classes

Guido Neele · Accepted Answer · 2018-11-13 10:38:15Z

4

Build complete solution and see where it fails. I had some NuGet projects hidden away in a folder that didn't build. Only while rebuilding the solution I found out what the problem was. Everything needs to build or else Scaffold will fail.

answered Nov 13, 2018 at 10:38

Guido Neele

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1 Comment

Becca Over a year ago

This did not reveal the issue for me. Visual Studio kept building successfully, even after cleans. Adding the --verbose flag to dotnet ef scaffold did not help. I had to do a dotnet build to see the error.

Inam Ul Huq · Accepted Answer · 2018-12-30 14:25:24Z

4

If entity-framework returns build failed, most probably you have some kind of error in any of your projects.

Even if the project you are running the command on, is clean and error-free, other projects in that solution can cause the build failed response.

Solution

Rebuild the whole solution. Most probably you'll find that error in solution-rebuild process.
Make sure the project you want to run command on, is selected in Default project drop-down inside Package Manager Console
Re-run the command.

answered Dec 30, 2018 at 14:25

Inam Ul Huq

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Muhammet Bozkan · Accepted Answer · 2019-07-02 13:37:18Z

4

If you use multiple projects in the solution, check the default project in the package manager.

answered Jul 2, 2019 at 13:37

Muhammet Bozkan

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user1499903 · Accepted Answer · 2020-04-23 21:34:40Z

4

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

answered Apr 23, 2020 at 21:34

user1499903

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Austin_Anderson · Accepted Answer · 2017-10-30 15:37:59Z

3

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

answered Oct 30, 2017 at 15:37

Austin_Anderson

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ashkufaraz · Accepted Answer · 2021-11-13 08:53:46Z

3

I has same Build Fails Error...

I after close visual studio and open again it, run Clean Solution and then Rebuild Solution from Build Menus after this Scaffold-Dbcontext build successfully

answered Nov 13, 2021 at 8:53

ashkufaraz

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Cpt.Ohlund · Accepted Answer · 2019-01-11 09:57:52Z

1

For me, my project built in Visual Studio but I had to specify a version for "Microsoft.AspNetCore.App" when running Scaffold-DbContext.

So instead of:

<PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
    <RuntimeFrameworkVersion>2.1.6</RuntimeFrameworkVersion>
</PropertyGroup>
<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App"/>
</ItemGroup>

I had to have:

<PropertyGroup>
    <TargetFramework>netcoreapp2.1</TargetFramework>
</PropertyGroup>
<ItemGroup>
    <PackageReference Include="Microsoft.AspNetCore.App" Version="2.1.6" />
</ItemGroup>

answered Jan 11, 2019 at 9:57

Cpt.Ohlund

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groenhen · Accepted Answer · 2019-12-13 17:18:20Z

1

Make sure your build works fine.
Run the scaffold command from the package console, your command should work:

Scaffold-DbContext 'Data Source=TEST-XY010;Initial Catalog=TESTDB;Trusted_Connection=True' Microsoft.EntityFrameworkCore.SqlServer -Context HOPWAContext -OutputDir TESTModel -Force

edited Dec 13, 2019 at 17:18

groenhen

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answered Dec 13, 2019 at 16:54

Shakil

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tblev · Accepted Answer · 2020-06-04 20:54:28Z

1

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

answered Jun 4, 2020 at 20:54

tblev

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Viktor38 · Accepted Answer · 2023-08-11 15:56:02Z

I had the same problem, but to me, it happened when I made EF -Migrations. This error can cause both when you add a command for Migration (what was my case) or Scaffolding the DB. When you start the command, first, it builds the project and if there is a problem during the build process, it stops, does not continue, and returns just "Build failed" message. There is no Log Error message or additional information about the problem. The previous answers are correct. Firstly and mainly you have to check if there is no compile error and the project is building successfully.

Right-click on the project level: Clean.
Right-click on the project level: Build.

Or if you have multiple projects in one solution is better to do this at the Solution Level to check the entire application.

Let me say about my case where I have the same problem.

I have a large application with multiple projects in 1 solution which are not related

Without: Add > Project Reference...

to each other i.e. Microservices and what made it difficult for me to do a Migration and get -

Builder Failed

in one of the services i.e. "Order API". The problem was in another service, i.e. "Basket API" I made some changes earlier here, injecting an extra dependency in the constructor in that API Controller, and without noticing that it was missing mocking this dependency for this Controller where I did a unit test which causes Compile Error. As "Order API" was a startup project and my focus was here, didn't show me the compile error through the Re-Building only the Order API, but there was a problem when I was adding the migration in the Order API and the cause of the problem was in the Basket API > Integration Test.

This is the example of my project solution:

I hope I explained well what happened in my case with "EF Migration - Builder Failed"; maybe it will be useful information.

Also you can try to turn off visual studio, restart your PC and try again.
I found some link about **EF - Scaffold ** Builder Failed:

Scaffold-Dbcontext build failed using EFCore commands

Your answer could be improved with additional supporting information. Please edit to add further details, such as citations or documentation, so that others can confirm that your answer is correct. You can find more information on how to write good answers in the help center.

Regianni · Accepted Answer · 2020-05-27 12:20:49Z

0

This stopped working for me today. So I tried running the dotnet scaffold command from the command line and it worked first time. Don't ask me!!

answered May 27, 2020 at 12:20

Regianni

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1 Comment

Regianni Over a year ago

It broke again before I discovered the --verbose flag, which delivered the stacktrace which allowed me to identify the problem. Would probably help if the error was output irrespectively of this flag.

admalledd · Accepted Answer · 2021-09-20 22:43:46Z

I had a issue that I have some non-scaffolded code in my DbContext project (partial classes for interfaces) that relied on generated files. As part of the re-scaffold though, I delete all previously generated code and of course this causes the project to fail building and thus scaffolding.

My work around is to have a custom "Scaffold" configuration on the project that simply removes from compilation a whole subfolder where any code-gen dependent files are to live.

If this is a path for you, edit your DbContext's .csproj and add:

<ItemGroup Condition="'$(Configuration)' == 'Scaffold'">
    <Compile Remove="NonGenerated\**\*.*" />
</ItemGroup>

and change your command line to include a --configuration Scaffold parameter. A powershell sample of how I do this is as such:

# Run from DbContext project root
$DbContextProjName = "Engine.Common.Dal"
#conStr = "...." #Your ConnectionString here, or loaded otherwise
if (Test-Path "Generated"){
    Remove-Item -Recurse -Force "Generated"
}

#Entities/Context in own folder for easy delete then regen, entity-dependant files go in NonGenerated
dotnet ef dbcontext scaffold `
    $conStr `
    "Microsoft.EntityFrameworkCore.SqlServer" `
    --context DatabaseContext `
    --data-annotations --force --no-onconfiguring `
    --namespace "$($DbContextProjName)" `
    --output-dir "Generated" `
    --project "$($DbContextProjName).csproj" `
    --startup-project "$($DbContextProjName).csproj" `
    --configuration "Scaffold"
if (! $?){
    throw "dotnet ef scaffold failed!"
}

Tuan Hoang · Accepted Answer · 2023-08-22 11:09:24Z

0

In my case, I run Scaffold-DbContext ... to generate the models. Then, I delete the generated models, run the command and it says Build failed.

What I have to do is to delete the generated context file generated by Scaffold-DbContext also and run the command again and it works for me.

answered Aug 22, 2023 at 11:09

Tuan Hoang

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S.Bozzoni · Accepted Answer · 2023-10-04 16:51:41Z

0

In my case it was the MSSQL management studio that was down , so the build couldn't work

answered Oct 4, 2023 at 16:51

S.Bozzoni

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Ivan Cardozo · Accepted Answer · 2019-12-09 21:08:05Z

-1

Make sure you have all packages and press ctrl + shift +b to build the solution. It works to me.

answered Dec 9, 2019 at 21:08

Ivan Cardozo

1

1 Comment

Gert Arnold Over a year ago

As the accepted answer already said years before. "Make sure that your project builds completely before you run a new scaffold command."

José Maurício · Accepted Answer · 2020-09-07 11:18:15Z

-1

Make sure your project is not running
Make sure your project is compiling

That worked for me.

answered Sep 7, 2020 at 11:18

José Maurício

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maneesh kumar gautam · Accepted Answer · 2021-01-20 13:33:45Z

-1

1-

Make sure the build is successful, to check to build is successful go-to solution explorer and right-click on solution name and rebuilt solution, all project will build successful and good to go.

2-

Install NuGet package Microsoft.EntityFrameworkCore.SqlServer

Install NuGet package Microsoft.EntityFrameworkCore.Tools

Install NuGet package Microsoft.EntityFrameworkCore.Design

check all the versions should be the same for NuGet packages like (3.1.3) and install inside class library if you are following onion architecture.

3-

Try now if still, it failed check db context and reference to class library should be added inside asp.net core web project.

answered Jan 20, 2021 at 13:33

maneesh kumar gautam

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"Build failed" on Database First Scaffold-DbContext

24 Answers 24

Two most important tips:

Other problems:

For EF Core 2

For EF Core 3

Full Scaffolding reference:

EF Core 2:

EF Core 3:

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Two most important tips:

Other problems:

For EF Core 2

For EF Core 3

Full Scaffolding reference:

EF Core 2:

EF Core 3:

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