ASP.NET Core EF Add-Migration command not working

Question

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

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.
I've latest release of ASP.NeT Core 1.0 and VS2015-Update 3 on windows 8.1
This is a freshly created project. No other DbContext was manually installed

The error text is describing the reason and what should you do. — Hamid Pourjam, Jul 02 '16 at 16:29
Also, the code should be part of the question. The link is broken, rendering the question into an empty shell. — Gert Arnold, Aug 30 '23 at 11:19

score 77 · Accepted Answer · edited Oct 18 '20 at 09:33

77

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

edited Oct 18 '20 at 09:33

shA.t

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answered Jul 02 '16 at 17:31

nam

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meanwhile the `-Context` changed to `-c` from what i could test – alexo Nov 25 '16 at 22:04
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It should be `--context` in .net core 2.0. – KaraKaplanKhan May 10 '18 at 10:28
is it possible that several contexts are same in **name** but diff only in **namespace**? – Lei Yang Aug 11 '21 at 15:45

score 19 · Answer 2 · answered Jan 31 '18 at 11:06

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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.

answered Jan 31 '18 at 11:06

John

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Isn't the issue that there are multiple db contexts? Do we need multiple contexts? How do we identify & delete them?? – timk Dec 24 '18 at 11:49
no. This is not an issue with multiple db contexts. We can use multiple db contexts, for example in multi tenant architecture it requires multiple db contexts. So there are situations where multiple db contexts required. – John Jan 31 '19 at 17:37
Didn't list what to do if you have multiple contexts. What if I have 10? Do I list `--context` 10 times??? – C.J. Sep 03 '20 at 19:21

score 15 · Answer 3 · answered Jan 29 '20 at 11:28

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If you need only update a identity schema existent, try it:

update-database -Context ApplicationDbContext

ApplicationDbContext = your identity context

answered Jan 29 '20 at 11:28

Diego Venâncio

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score 4 · Answer 4 · answered Jul 02 '16 at 17:34

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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

answered Jul 02 '16 at 17:34

Mohammad Al Safra

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score 2 · Answer 5 · edited Apr 07 '20 at 08:36

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Add-Migration MyFirstMigration -Context DbContextName

It does work in my project.

edited Apr 07 '20 at 08:36

Amit Joshi

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answered Apr 07 '20 at 08:06

Mohsen.bakhtiyariha

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score 1 · Answer 6 · edited Mar 04 '21 at 10:13

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Use below to commands:

PM> Add-Migration MyFirstMigration -Context YourDbContext

PM> update-database -Context YourDbContext

edited Mar 04 '21 at 10:13

juagicre

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answered Mar 04 '21 at 07:08

Harichandra Sagar

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what is the difference between Add-Migration and dotnet ef Initial Migration? – Marin Apr 30 '21 at 14:22

score 1 · Answer 7 · answered Nov 22 '21 at 14:50

[--context]

The DbContext class to use. Class name only or fully qualified with namespaces. If this option is omitted, EF Core will find the context class. If there are multiple context classes, this option is required.

Add-Migration MyMigration -context DataContextName

ASP.NET Core EF Add-Migration command not working

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