EF Core add-migration Build Failed

Question

I have a developer that is getting  Build failed   when running add-migration in a  NET Core EF project  with no explanation of why the build failed  How do you troubleshoot this error   This is what he gets in the Package Manager Console   Additional information   We have a few other developers using the same solution code  myself included  that have not issues with add-migration   This is what I see in Package Manager Console   We ve verified that the project builds  and the entire solution builds  We ve done  dotnet restore  and rebuild all multiple times  in addition to restarting VS2015  We ve verified that the correct default solution is selected both in Solution Explorer  and in the Package Manager Console drop-down  We ve verified that he has the correct SDK installed on his machine  I m at a loss as to what to check next   any time I ve had a failure during add-migration I ve gotten enough information to point me in the direction of what to check  but just  Build failed   is a fairly useless error output

User · Answer

I had the same error   What I did  I corrected the error the one I have in code  and rebuilt the project  Then I ran the ms-dos command and it worked

User · Answer

I was struggling with this one while using Visual Studio 2019 version 16 5 0   What solved it finally    Close Visual Studio  Reopen Visual Studio  Make sure you right click the Solution if you have multiple projects and select Rebuild Solution    Note that I tried doing a Rebuild Solution before and that did not catch the error  So it s important to close VS and reopen it   It then showed the error that was causing add-migration command to fail with Build failed message

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Turns out this could also be caused by BuildEvents  For me I was referencing   SolutionDir  there  With a regular build this variable has value  but running dotnet   commands is done at project level apparently    SolutionDir  comes out like Undefined in verbose mode  -v   This seems like a bug to me

User · Answer

Got the same error when I tried to run add-migration  Make sure that you don t have any syntax errors in your code   I had a syntax error in my code  and after I fixed it  I was able to run add-migration

User · Answer

In my case it was because i had error somewhere   Like missing coma in db config file  so VS didn t throw exception until build  So just try to run your code

User · Answer

It s because of other projects in your solutions  e g If you have two projects in your solution as Project A and Project B  If Project A is not successful build and then Project B data migration will fail  So you should unload Project A and add the migration to Project B again   I think this is not a good answer but hope this help

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I had exact same error but I am using Visual Studio Community 2017 Version 15 2  26430 14  to build  Net Core projects   I have a ASP NET Core MVC web project and a separate security project using ASP NET Core Identity  The web project contains connection string in aspsettings json config file   I also installed Bundler  amp  Minifier and Web Essentials 2017 extensions in Visual Studio so that I can compile  minify and bundle my assets and put them to wwwroot   I figured out it was the MSBuild those 2 extensions secretly download that caused the problem  because I had Enable Bundle on Build and Enable Compile on Build on  After I disable that  everything works fine   Probably not the cause to your problem  but might be worthy to just give it a try

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I had the exact same problem   NET Core 2 0 1   Sometimes it helps if the project is rebuilt  I also encounter the problem when I opened the project in 2 Visual Studios  Closing one Visual Studio fixed the error

User · Answer

I think the 2 commands below always work  if you run them at project s folder    dotnet ef migrations add   database object fron ApplicationDbContextDBContext  dotnet ef database update

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I suggest adding -v to have more info   In my example  I had to add   lt LangVersion gt latest lt  LangVersion gt  to my projects  as this was missing from some of them

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In my situation it was the error  namespace aspnetcore does not exist    are you missing a reference    I have figured it out by adding the -v  or --verbose  flag to the dotnet ef command

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Only clearing Visual Studio cache helped me  Close Visual Studio  ensure devenv exe is not present in the Task Manager  Delete the  USERPROFILE  AppData Local Microsoft VisualStudio 16 0 ComponentModelCache directory  Restart Visual Studio  You could also need to cleanup your user s temp folder  It is usually located under  USERPROFILE  AppData Local Temp

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In my case  the application was running  Apparently  it needs to be stopped  Weird error message anyways

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Try saving DataContext cs first  It worked for me

User · Answer

In my case I had couple of such errors  The process cannot access the file  C  xxx bin Debug netcoreapp3 1 yyy dll   because it is being used by another process   C  zzz csproj   I was able to see those errors only after adding -v parameter  The solution was to shutdown the Visual Studio and run the command again

User · Answer

I got the same error  There were no errors during the build proccess  I closed the Visual Studio and it worked

User · Answer

Try these steps   Clean the solution   Build every project separately   Resolve any errors if found  sometimes  VS is not showing errors until you build it separately    Then try to run migration again

User · Answer

Open Output window in Visual Studio and check your build log  In my case  even though my current configuration was Release  Add-Migration built the project in Debug  which had an error  For some reason  VS didn t display the error anywhere except Output window for me

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In My case  add the package Microsoft EntityFrameworkCore Tools fixed problem

User · Answer

Same errors for me  I tried -v but nothing  Then I realised I had changed the model so much that the controller was showing errors    Once I fixed the errors in the controller it worked

User · Answer

I had the same problem when running   dotnet ef migrations add InitialCreate  so what I did is tried to build the project using   dotnet build command   It throws an error   Startup cs 20 27   error CS0103  bla bla for example  which you can trace to find the error in your code   Then i refactored the code and ran   dotnet build again  to check any errors until there is no errors and build is succeded  Then ran  dotnet ef migrations add InitialCreate then the build succeded

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Just got into this issue  In my case  I was debugging my code and it was making my migrations fail  Since in Visual Studio Code  the debugger is so low-profile  only a small bar   I didn t realize about this until I read some questions and decided to look better

User · Answer

I got the same error  I fixed it by stopping the project build  After that it worked fine

User · Answer

I think this happened to me when I tried to run dotnet ef migrations add xyz whilst it was already running    In the end  just to be sure  I stopped the currently running instance  then ran it again to ensure it was rebuilt  stopped it again and I was able to run the dotnet ef migrations add command

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The developer ended up un-mapping the project from TFS  deleting it  and re-mapping it  It s now working for him

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In my case rebuilding the Project worked fine  Running the project worked fine too and executing some endpoints worked  But still on update-database it would say  quot Build Failed quot  without any clarification  even with -Verbose added to the command  At the end it happened that there was an error in Unit Test project that would  for some reason  cause  quot Build Failed quot  error  Since I have multiple projects under the same Solution  I would just rebuild the Project that I am currently working on  It appears that when this error happens that it would be better to rebuild whole Solution and resolve errors

User · Answer

Had the same situation  This helped   Open Package Manager Console  Change directory to Migrations folder  cd C  YourSolution YourProjectWithMigrations   Enter in PM  dotnet ef migrations add YourMigrationName

User · Answer

1  I was getting the error  PM  Add-Migration  InitialDB  Build failed  2 The error was the     missing  I corrected that and error is gone   so the error you can see the error in the output  The error was because of the code issue

User · Answer

It might have many possibilities I guess  In my case  it was due packages versions inbalance I had  lt PackageReference Include  quot Microsoft EntityFrameworkCore quot  Version  quot 3 1 1 quot   gt   lt PackageReference Include  quot Microsoft EntityFrameworkCore Design quot  Version  quot 3 1 3 quot   gt   I just need it to downgrade the core Design package to 3 1 1 to match the upper core version  lt PackageReference Include  quot Microsoft EntityFrameworkCore quot  Version  quot 3 1 1 quot   gt   lt PackageReference Include  quot Microsoft EntityFrameworkCore Design quot  Version  quot 3 1 1 quot   gt   Then it worked fine

User · Answer

In my case it was failing because an unrelated project in the solution was failing  Unloading that project and running the command again worked

User · Answer

maybe it cause because of you did not add this in YOUR PROJECT csproj   lt ItemGroup gt    lt DotNetCliToolReference Include  Microsoft EntityFrameworkCore Tools Dotnet  Version  2 0 2    gt

User · Answer

Most likely that there is an existing error in your code  Try rebuilding first and correct all the errors    Happened to me  I am trying to rollback migration but I have not corrected the errors in the code yet

User · Answer

this is because deleting projects or class libraries from solution and adding projects after deleting with same name              best thing is delete solution file and add projects to it this works for me  I did this using vsCode

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Make sure you have code generation inside startup cs  Example   lt Project Sdk  Microsoft NET Sdk Web  gt    lt PropertyGroup gt   lt TargetFramework gt netcoreapp2 1 lt  TargetFramework gt   lt  PropertyGroup gt    lt ItemGroup gt   lt PackageReference Include  Microsoft AspNetCore App    gt    lt PackageReference Include  Microsoft EntityFrameworkCore Sqlite  Version  2 1 2    gt   lt PackageReference Include  Microsoft VisualStudio Web CodeGeneration Design  Version  2 1 3    gt    lt  ItemGroup gt    lt  Project gt

[.net] EF Core add-migration Build Failed

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