ASP.NET Core EF Add-Migration command not working

问题

Following this Microsoft Tutorial when I run the PM> Add-Migration MyFirstMigration command in VS2015 project created from the same tutorial I get the following error that I can't resolve:

More than one DbContext was found. Specify which one to use. Use the '-Context' parameter for PowerShell commands and the '--context' parameter for dotnet commands.

Point to note

1. I'm using the above tutorial with the exception that I'm using Individual User Account authentication instead of No Authentication used in the tutorial.
2. I've latest release of ASP.NeT Core 1.0 and VS2015-Update 3 on windows 8.1
3. This is a freshly created project. No other DbContext was manually installed

回答1:

Running the following command (obtained from this article) and a response from @Maverik (from STackoverflow here) and a suggestion from @doctor above helped me resolved the issue. Thank you all for your help:

PM> Add-Migration MyFirstMigration -Context BloggingContext

回答2:

The error clearly explains to mention --context with db Context name if more than one DbContext. So try by mentioning your DbContext name.

dotnet ef migrations add Initial --context SampleDbContext

Hope this helps.

回答3:

that because you have two DbContext in your solution. First is default created when you creating project(ApplicationDbContext) and second your EF DbContext. Solution is described in error message just specify your EF DbContext

来源：https://stackoverflow.com/questions/38162227/asp-net-core-ef-add-migration-command-not-working