Adding migration doesn't work and gives no useful error message-CodePudding

I'm using EF 6.0.12 and when adding migrations to my project, basically this happens:

Visual Studio:

PM> add-migration Initial
Build started...
Build failed.

CLI:

D:\myproject\db>dotnet-ef migrations add Init
Build started...
Build succeeded.
Unable to create an object of type 'RequestContext'. For the different patterns supported at design time, see https://go.microsoft.com/fwlink/?linkid=851728

Which is as useful as a brick in my face. It gets me really annoyed. And I have no clue on how to solve this as there's no useful error message...
Now, I use these packages in my project:

Microsoft.EntityFrameworkCore Version 6.0.12
Microsoft.EntityFrameworkCore.Tools Version 6.0.12
Pomelo.EntityFrameworkCore.MySql Version 6.0.2

And my DBContext is inside a Class library, and is used by a Web API. Which works quite well, but I now need migrations.
The problem is that my database is MariaDB and the MySQL package I need does not support .NET 7.0, nor do I use 7.0 so the EF7 packages are off-limits. But my problem is that I just don't know how I can even start finding the cause of this problem. So, where do I start to try and make this work?

I've tried to solve things by migrating the project to .NET 7.0 and now use the latest packages:

Microsoft.EntityFrameworkCore 7.0.1
Microsoft.EntityFrameworkCore.Tools 7.0.1
MySql.EntityFrameworkCore 6.0.7

These are all the latest versions. And Pomelo.EntityFrameworkCore.MySql has been removed. Still, it changes nothing about the error I get.
Some more changes made to the code and finally got past this error in the CLI and VS. I now have this exception:

PM> add-migration Katje-Init
Build started...
Build succeeded.
System.Reflection.TargetInvocationException: Exception has been thrown by the target of an invocation.
 ---> System.MissingMethodException: Method not found: 'System.String Microsoft.EntityFrameworkCore.Diagnostics.RelationalStrings.get_NoConnectionOrConnectionString()'.
   at MySql.EntityFrameworkCore.Internal.MySQLOptions.GetConnectionSettings(MySQLOptionsExtension relationalOptions)
   at MySql.EntityFrameworkCore.Internal.MySQLOptions.Initialize(IDbContextOptions options)
   at Microsoft.EntityFrameworkCore.Internal.SingletonOptionsInitializer.EnsureInitialized(IServiceProvider serviceProvider, IDbContextOptions options)
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<GetOrAdd>g__BuildServiceProvider|4_1(IDbContextOptions _, ValueTuple`2 arguments)
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.<>c.<GetOrAdd>b__4_0(IDbContextOptions contextOptions, ValueTuple`2 tuples)
   at System.Collections.Concurrent.ConcurrentDictionary`2.GetOrAdd[TArg](TKey key, Func`3 valueFactory, TArg factoryArgument)
   at Microsoft.EntityFrameworkCore.Internal.ServiceProviderCache.GetOrAdd(IDbContextOptions options, Boolean providerRequired)
   at Microsoft.EntityFrameworkCore.DbContext..ctor(DbContextOptions options)
   at RequestDatabase.RequestContext..ctor(DbContextOptions`1 options) in D:\Projects\DB\Datamodel.cs:line 16
Etc...

The CLI gives the same exception now. Not sure how I fixed the previous error, but it's still very unclear. So again, what is the best approach to solve these complex errors?

CodePudding user response：

The last error shows that there is breaking change (usually sign of a version mismatch between the packages). As in this answer - switch from Oracle MySQL package to Pomelo preview one for .NET 7.