I am adding a new migration but this message shows:
Unable to generate an explicit migration because the following explicit migrations are pending: [201203170856167_left]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
Can any one help me?
This error can also mean that the migrations are not recognized anymore. This happened to me after having changed the value of the ContextKey in Migrations.Configuration. The solution was simply to update the ContextKey in the database table "__MigrationHistory" (or revert the value in the Configuration class I guess). The ContextKey and the Namespace in your application should match.
Check the connection string again.
Make sure the user you are connecting with still has permission to read from [__MigrationHistory] and has permission to edit the schema.
You can also try changing the connection string in the App or Web config file to use Integrated Security (Windows Auth) to run the add-migration command as yourself.
For example:
connectionString="data source=server;initial catalog=db;persist security info=True;Integrated Security=SSPI;"
This connection string would go in the App.config file of the project where the DbContext is located.
You can specify the StartUp project on the command line or you can right click the project with the DbContext, Configuration and Migrations folder and select Set as StartUp project. I'm serious, this can actually help.
Had the same issue and was able to solve with some hints from above answers:
Use "update-database -verbose" in the package manager console to get more specific information where migrations tries to connect to. (Helped in my case to find out my startup proj was not set correctly...)
If you haven't used Update-Database you can just delete it. If you've run the update then roll it back using Update-Database -TargetMigration "NameOfPreviousMigration", then delete it.
Reference: http://elegantcode.com/2012/04/12/entity-framework-migrations-tips/
I copied this text directly from here: How do I undo the last Add-Migration command?
When running into this issue, please try adding parameters to your add-migration cmdlet. For example, specifying the start up project as well as the connection string name could help EF find your target database.
add-migration Delta_Defect_0973 -ConfigurationTypeName your.namespace.ContextClassName -StartUpProject DeltaProject -ConnectionStringName DeltaSQL
Where:
Delta_Defect_0973 is the name of your migration
your.namespace.ContextClassName is the name of your Configuration class in your migration folder, prefixed with the full name space.
DeltaProject is the name of your main project with your web.config or app.config file.
DeltaSQL is the name of your connection string defined in your web.config or app.config file.
This error means there are pending migrations need to be commited before you can execute another explicit migration. You can choose to
After this one you can start "Add-Migration ..." again
Hope it helps
Just my two cents:
My scenario:
Solution:
To get around this i just provided more explicit parameters:
Add-Migration -ConnectionString "Server=localhost\SQLEXPRESS;Database=YourDataBase;Trusted_Connection=True;" -ConnectionProviderName "System.Data.SqlClient" -verbose
I am lead to believe that you can set a setting in your app.config folder to allow you to default this behaviour so you don't have to provide explicit parameters everytime. However I am not sure on how to do this.
Tip: It's always good to use the -Script switch for migration commands if you're not sure. It also really helps understand what Update-Database actually does.
I run the following to update the database, then I get a script I can apply manually (or just run it again without the -Script tag).
For Update-Database I would run the following :
Update-Database -Script -ConfigurationTypeName Configuration_ASPNETIdentity -ConnectionStringName SQL_AzureLive
Where SQL_AzureLive is the named connection string in my config.
Then I can verify the SQL looks right, apply it and be done. As many others have said if the connection string is wrong or invalid you'll get this error.
Scenario
Problem
After updating from master, I run "Add-Migration my_migration_name", but get the following error:
Unable to generate an explicit migration because the following explicit migrations are pending: [201607181944091_AddExternalEmailActivity]. Apply the pending explicit migrations before attempting to generate a new explicit migration.
So, I run "Update-Database" and get the following error:
Unable to update database to match the current model because there are pending changes and automatic migration is disabled
Solution
At this point re-running "Add-Migration my_migration_name" solved my problem. My theory is that running "Update-Database" got everything in the state it needed to be in order for "Add-Migration" to work.
In my case, I forgot to add my IP address in firewall rules in Azure, basically as I was unable to connect to the database I was getting this error. So specifically for my case, I added my IP address in database firewall rules in Azure and it all worked well. Apart from this, it could be the issue of proxy/internet connection/DB username password/DB connection string etc. OR obviously, you might have pending migrations for which you need to run Update-Database command.
Historically I always solved this by deleting the pending migrations, or if there was only 1 remaining and it was mostly desirable, by using -f to recreate it.
Recently, this has stopped working for me.
When this happened the first time, I restarted Visual Studio, and then it let me proceed.
The second time, it only worked after I ran a Clean on the project. It was almost as if the pending migrations were retained despite deleting all the files from explorer.
Old post but might help someone.
For me it happened because I renamed Assembly name and Default namespace of the project.
So I had to update ContextKey in _MigrationHisotry table to the new value of Assembly name or Default namespace. Honestly I don't know which one should be used, because for me both are same!
I suffered exactly the same problem just after reverting from a migration to another.
In my case I "targetedmigration" from "migration06" to "migration04".
I needed to delete the "migration0"6 and then I was able to force creating the "migration05". This basically means that you need to just keep the next migration after the targeted one.
