Why am I getting a contentRootPath null exception when attempting to add a database migration in entityframework core?

Question

I have a .NET Core class library that is the data access layer for multiple web applications. I am using Entity Framework Core 1.1, but I'm having trouble with migrations through PMC. My initial migration worked successfully, but after updating the database and re-launching VS 2017 I get a null exception on the contentRootPath argument when attempting to migrate. I may have made some changes to the project after my successful migration, but I don't remember what they were. This is the error and stack trace:

Both Entity Framework Core and Entity Framework 6 are installed. The Entity Framework Core tools are running. Use 'EntityFramework\Add-Migration' for Entity Framework 6. System.ArgumentNullException: Value cannot be null. Parameter name: contentRootPath at Microsoft.EntityFrameworkCore.Utilities.Check.NotEmpty(String value, String parameterName) at Microsoft.EntityFrameworkCore.Design.Internal.MigrationsOperations..ctor(IOperationReporter reporter, Assembly assembly, Assembly startupAssembly, String environment, String projectDir, String contentRootPath, String rootNamespace) at Microsoft.EntityFrameworkCore.Design.OperationExecutor.<>c__DisplayClass4_0.<.ctor>b__4() at Microsoft.EntityFrameworkCore.Internal.LazyRef`1.get_Value() at Microsoft.EntityFrameworkCore.Design.OperationExecutor.AddMigrationImpl(String name, String outputDir, String contextType) at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.<>c__DisplayClass3_0`1.<Execute>b__0() at Microsoft.EntityFrameworkCore.Design.OperationExecutor.OperationBase.Execute(Action action)

There is no config file in my migrations directory, and I can't find anything related in the DbContext class. Has anyone else ran into this issue, or know what is causing it?

SqlDbContext class:

using Microsoft.EntityFrameworkCore; using DataLayer.Models.User; namespace DataLayer.Context { public class SqlDbContext : DbContext { public DbSet<User> Users { get; set; } protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) { optionsBuilder.UseSqlServer(MyDbConfig.SqlConnectionString); } protected override void OnModelCreating(ModelBuilder modelBuilder) { modelBuilder.Entity<User>() .Ignore(m => m.FullName); base.OnModelCreating(modelBuilder); } } }

I edited your tags... to only show EFC. Can you show us your references? Startup.cs and appsettings.json — mvermef
– mvermef, Commented Jun 22, 2017 at 19:52
It's in a Class Library, so there is no Startup.cs or appsettings.json files. I am just storing my connection string in a static class, along with connection strings to other databases that I am accessing. I updated the code snipped with my references. And my mistake before, I meant that EF6 is in the solution, not the project. — dzlp
– dzlp, Commented Jun 23, 2017 at 2:08
I just looked at my Nuget packages, and for some reason my EntityFrameworkCore.Tools package was a pre-release version (2.0.0). I just downgraded to 1.1.1, and now migrations are working again. Not sure why it updated to an unstable version, but it's working now. Thanks anyway for you help! — dzlp
– dzlp, Commented Jun 23, 2017 at 2:18

Brian Ogden · Accepted Answer · 2017-09-01 16:59:09Z

1

It turns out that this was due to the Microsoft.EntityFrameworkCore.Tools package being pre-release version 2.0.0, which is not currently a stable version. Downgrading to 1.1.1 fixed the issue.

edited Sep 1, 2017 at 16:59

Brian Ogden

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answered Jun 23, 2017 at 2:20

dzlp

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2 Comments

Brian Ogden Over a year ago

Are you sure that you do not mean 1.0.1?

Brian Ogden Over a year ago

There is no 1.1.1 version though

YManaf · Accepted Answer · 2018-11-21 20:52:40Z

I had this issue in the past and here is the fix:

First, make sure that the version of the SDK you are using is 2.1.200 as you are under Core 1.1 and put this on your global.json:

{ "sdk": { "version": "2.1.200" } }

Add reference on your .csproj to Microsoft.EntityFrameworkCore.Design and Microsoft.EntityFrameworkCore.Tools.DotNet so you will have:

 <ItemGroup> <PackageReference Include="Microsoft.EntityFrameworkCore.Design" Version="1.1.6" PrivateAssets="All" /> </ItemGroup> <ItemGroup> <DotNetCliToolReference Include="Microsoft.EntityFrameworkCore.Tools.DotNet" Version="1.1.6" /> </ItemGroup>

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