Efcore: MissingMethodException: Method not found: 'Boolean Microsoft.EntityFrameworkCore.Migrations.IMigrationsModelDiffer.HasDifferences

[Lionberg]

Describe the bug

Newly generated Blazor project cannot be run with last version of EntityFrameworkCore.

To Reproduce

1. Generate new Blazor Server project with Authorization.
2. Update Nuget Packages to version 5.0.0-rc.1.20451.17: EntityFrameworkCore, microsoft.aspnetcore.identity.ui
3. Build and Run the project.

Expected result:
Project is run.

Actual Result:
While updating packages, the code generator adds line to AssemblyInfo.cs file:
[assembly: Microsoft.AspNetCore.Identity.UI.UIFrameworkAttribute("Bootstrap4")]
which cause compiler error: ProjectName.AssemblyInfo.cs(13, 42): [CS0234] The type or namespace name 'UI' does not exist in the namespace 'Microsoft.AspNetCore.Identity' (are you missing an assembly reference?)

If this generated line is deleted, then I see Unhandled exception:
MissingMethodException: Method not found: 'Boolean Microsoft.EntityFrameworkCore.Migrations.IMigrationsModelDiffer.HasDifferences(Microsoft.EntityFrameworkCore.Metadata.IModel, Microsoft.EntityFrameworkCore.Metadata.IModel)'.

Exceptions (if any)

MissingMethodException: Method not found: 'Boolean Microsoft.EntityFrameworkCore.Migrations.IMigrationsModelDiffer.HasDifferences(Microsoft.EntityFrameworkCore.Metadata.IModel, Microsoft.EntityFrameworkCore.Metadata.IModel)'.

Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
System.Runtime.CompilerServices.AsyncMethodBuilderCore.Start(ref TStateMachine stateMachine)
System.Runtime.CompilerServices.AsyncTaskMethodBuilder.Start(ref TStateMachine stateMachine)
Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Raw exception details:
System.MissingMethodException: Method not found: 'Boolean Microsoft.EntityFrameworkCore.Migrations.IMigrationsModelDiffer.HasDifferences(Microsoft.EntityFrameworkCore.Metadata.IModel, Microsoft.EntityFrameworkCore.Metadata.IModel)'.
at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
at System.Runtime.CompilerServices.AsyncMethodBuilderCore.StartTStateMachine
at Microsoft.AspNetCore.Diagnostics.EntityFrameworkCore.DatabaseErrorPageMiddleware.Invoke(HttpContext httpContext)
at Microsoft.AspNetCore.Diagnostics.DeveloperExceptionPageMiddleware.Invoke(HttpContext context)

Further technical details

I was trying to downgrade versions, but nothing works.

output of dotnet --info:

.NET Core SDK (reflecting any global.json):
Version: 3.1.302
Commit: 41faccf259

Runtime Environment:
OS Name: Mac OS X
OS Version: 10.15
OS Platform: Darwin
RID: osx.10.15-x64
Base Path: /usr/local/share/dotnet/sdk/3.1.302/

Host (useful for support):
Version: 3.1.6
Commit: 3acd9b0cd1

.NET Core SDKs installed:
1.0.0-preview2-003121 [/usr/local/share/dotnet/sdk]
1.0.3 [/usr/local/share/dotnet/sdk]
2.0.0 [/usr/local/share/dotnet/sdk]
2.1.4 [/usr/local/share/dotnet/sdk]
2.1.302 [/usr/local/share/dotnet/sdk]
2.1.505 [/usr/local/share/dotnet/sdk]
3.1.200 [/usr/local/share/dotnet/sdk]
3.1.300 [/usr/local/share/dotnet/sdk]
3.1.302 [/usr/local/share/dotnet/sdk]

.NET Core runtimes installed:
Microsoft.AspNetCore.All 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.All 2.1.9 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.All]
Microsoft.AspNetCore.App 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 2.1.9 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.2 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.4 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.AspNetCore.App 3.1.6 [/usr/local/share/dotnet/shared/Microsoft.AspNetCore.App]
Microsoft.NETCore.App 1.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 1.0.4 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 1.1.1 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.0 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.0.5 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.9 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.18 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 2.1.20 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.2 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.4 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]
Microsoft.NETCore.App 3.1.6 [/usr/local/share/dotnet/shared/Microsoft.NETCore.App]

• The IDE (VS / VS Code/ VS4Mac) you're running on, and it's version
  JetBrains Rider 2020.2.3
  Build #RD-202.7319.2, built on September 17, 2020

[mkArtakMSFT]

@ajcvickers do you know whether there was any breaking change which could have caused this?

[ajcvickers]

@mkArtakMSFT Not that I am aware of. /cc @bricelam

@Lionberg Can you post the contents of your csproj file?

[mkArtakMSFT]

@Lionberg moving to EF repo so that you can deal with this there. Thanks!

[smitpatel]

https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-5.0/breaking-changes#relational-model

[ajcvickers]

@Lionberg Does following the guidance in the document linked by @smitpatel help you past this?

[AndriySvyryd]

@Lionberg Make sure to upgrade all ASP.NET packages to a matching 5.0 version

[AmSmart]

@Lionberg Make sure to upgrade all ASP.NET packages to a matching 5.0 version

I also get this issue, does this mean I can't use EFCore with .NET Core 3.1?

[ajcvickers]

@AmSmart No, it means that you will need to follow the guidance in the breaking changes docs: https://docs.microsoft.com/en-us/ef/core/what-is-new/ef-core-5.0/breaking-changes#relational-model

[AmSmart]

@ajcvickers

Oh! Thanks. Just tested it, it's working great. Absolutely loved your demo on Many to Many relationships. Great job from you and the team.

[ajcvickers]

@AmSmart Thanks. Glad you enjoyed it. :-)

[rudiv]

@AmSmart just to clarify in the documentation that @ajcvickers mentioned it gives updated code for the differ, but this isn't my code, it's internal to the DatabaseErrorPage.

For anyone else coming across this issue on a 3.1 -> 5.0 project (specifically: where ASP.NET Core 3.1 is being used still, but with EF 5.0), removing the call to app.UseDatabaseErrorPage() in Configure() will resolve the error on startup.