EF6 'DbConfigurationClass' was set but this type was not discovered - multiple DbContexts and DbConfigurations

Easiest solution seems to have been to move to config-file based configuration, as detailed here.

The reason I couldn't get this to work the first time is because I had a different version of EF listed in one of the various config files and didn't catch it.

I did try using a single DbConfiguration class in a common library and was able to get it to work this time (with no real fiddling, I must have just done something terribly wrong the first time) but I think that the config-file based configuration is the better solution.

Putting configuration information in a config file, how novel!

According to Microsoft you can solve two DbContexts with DbConfiguration like this:

XML:

<entityFramework codeConfigurationType="MyNamespace.MyDbConfiguration, MyAssembly">
    ...Your EF config...
</entityFramework>

Code:

[DbConfigurationType(typeof(MyDbConfiguration))]
public class MyContextContext : DbContext
{
}

[DbConfigurationType("MyNamespace.MyDbConfiguration, MyAssembly")]
public class MyContextContext : DbContext
{
}

https://docs.microsoft.com/en-us/ef/ef6/fundamentals/configuring/code-based

I did not solve multiple DbConfiguration however. My solution was sharing the same DbConfiguration for both DbContexts like this:

public class DbContextConfiguration : DbConfiguration
{
    public DbContextConfiguration()
    {
        var providerInstance = SqlProviderServices.Instance;
        SqlProviderServices.TruncateDecimalsToScale = false;
        this.SetProviderServices(SqlProviderServices.ProviderInvariantName, SqlProviderServices.Instance);
    }
}

[DbConfigurationType(typeof(DbContextConfiguration))]
public class DbContext1 : DbContext
{

}

[DbConfigurationType(typeof(DbContextConfiguration))]
public class DbContext2 : DbContext
{

}