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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?

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    This happened to me when I had accidentally switched my startup project to a different one. You (or others reading this) may want to check that quickly before trying some more in depth trouble shooting (especially ones where you have to start deleting migrations and such). Commented Apr 3, 2017 at 4:41
  • There is a migration class in Migrations directory which is not updated in the _MigrationHistory of the database. Removing that class to have same state both in Migration directory and database solved my problem. Commented Oct 4, 2018 at 15:08
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    This happens to me randomly. When it happens it shows that all my migrations need to be applied. I have to restart Visual Studio to get it to work because I already have everything set up properly. Commented Mar 24, 2020 at 18:47

32 Answers 32

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It tells you that there is some unprocessed migration in your application and it requires running Update-Database before you can add another migration.

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5 Comments

What I you want to recreate an initial migration? This blocks you from doing so?
Did not work for me,Update-Database just gave me another error. I had to delete the pending files first.
Thomas's answer was the useful one for my similar case.
It may be neccessary to declare a startup-project -StartupProject ContentHub.Database
Update-Database gives >Unable to update database to match the current model because there are pending changes
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I had the same problem. Apparently entity framework generates this error when it's unable to connect to the database. So make sure that you're able to access it before searching for other problems.

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6 Comments

I would also add that this would be the case when you move your App.config to another project or if it is just plain missing in your project or if it is in your project but is configured incorrectly.
I got this same error after my IP changed (happened both after switching location and after a dyn dns change). This caused the firewall in the Azure Database we are using to revoke the login. Unhelpfully EF migrations gives the above error instead of "could not log in"...
Another point I'd like to make is to make sure to check your startup project is one with your db context's connection string. I had this problem when I temporarily changed my startup project and didn't realize that the other project didn't have the same connection string.
Adding to @GageTrader : I had multiple startup projects , one with no config, and web project with EF-config. the (Repository) project with migrations has the same EF config in its app.config as the web project. but even when I selected the repository project as startup project it didnt work, but when I set the web project to startup it did.
I had to explicitly state the -ConnectionString parameter, which did the trick for me
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You either need to run "update-database" from the package manager console to push your changes to the database OR you can delete the pending migration file ([201203170856167_left]) from your Migrations folder and then re-run "add-migration" to create a brand new migration based off of your edits.

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2 Comments

I deleted the migration file and ran add-migration, but it still gives the same error.
Thanks, the tip about deleting the pending migration file was a lifesaver
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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.

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5 Comments

That was the right answer for my case. As I used one of my old projects for a new similar project, I wasn't able to make changes to the DB over the old migrations. As Thomas suggested, the namespace was different in the Migrations from the Contextkey in the _MigrationsHistory table, that caused old migrations not to be recognised.
This helped me because I caused the problem by renaming the solution. In the process I had renamed the ContextKey so it no longer matched the _MigrationHistory entries.
Also worked for me, set an explicit context key in the configuration, changed it in the __MigrationHistory and update-database decided everything was cool. Thanks!
Ridiculous, but it's right. If you updated project name, or if you split you project (my case) into few and you are trying to add new migration from a new project to the same db, you have to use correct ContextKey, you can set it in Configuration constructor (you have to use the Context key you have in __MigrationHistory table in target DB)
same here, i renamed my default name space and replaced it throughout my solution which caused this issue
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1. Connection String / Connection Permissions

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.

2. StartUp Project

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.

enter image description here

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7 Comments

Haha. I wish this would get more up votes. This happens to me a lot and the Integrated Security fix works great!
I had the same issue, none of the migration commands worked. Turns out not setting the startup project was the culprit. Setting that fixed my issue.
Changing the startup project worked for me ! I was sure it wouldn't work but I tried it anyway since everything else failed. Great answer.
"Set as Startup" - never would have guessed! Thank you!!
Yep, I've intentionally changed startup project, and forgot to change it back. And funny is, that one migration before was done with proper startup project, so everything worked fine. But this is logical now - b/c EF takes connection string from the project, thus it "does not know" that migrations actually already applied to DB...
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Had the same issue and was able to solve with some hints from above answers:

  • In package manager console check the default project (point to the project with the migration configuration
  • Ensure the startup-proj has a web.config with a valid connectionstring ( or
  • Ensure the project with migrations has an app.config / web.config with a valid connectionstring
  • Check permissions in DB (for the user configured in you connectionstring)

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...)

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2 Comments

ran "update-database -verbose" and noticed that my connection string was broken, lol. So add-migration command gives the wrong message.
"Ensure the startup-proj {...}" solved my problem. Thanks @flex
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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?

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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.

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1 Comment

Also, if you are using dependency injection in your solution, you may have to select a different Default Project in the Package Manager Console. If EF is unable to locate your migrations, try selecting the project that actually contains the migrations as the default project.
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This error means there are pending migrations need to be commited before you can execute another explicit migration. You can choose to

  1. Execute those pending migrations using Update-Database command
  2. Delete those pending migrations. Safest way is open Migrations folder, right click on [201203170856167_left] > Exclude from project

After this one you can start "Add-Migration ..." again

Hope it helps

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6

i solved same problem like this:

  • delete old migration file
  • update-database -force
  • Add-Migration AddedEntity
  • update-database
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Just my two cents:

My scenario:

  1. I restored my local database to a working state.
  2. Already had migrations already applied to it.
  3. Whenever I tried adding a new migration i got the error about pending migrations as mentioned my the OP.

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.

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4 Comments

This worked for me, I just added the name of the migration to the end of the command shown above.
= ) - glad i could help.
-ConnectionStringName is an alternative to this, and will pull the connection string from your config by name
This helped me because I am not storing the connection string in the config file
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This isn't going to be the answer for many people, but EF will chuck this error when it can't connect to the DB. If you're working from home like I am, make sure you're still connected to your VPN!

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There is an ambiguity and so error. Best way is to exclude the current migration file and create new migration(add-migration) file and then copy the content of new migration to excluded file and include it again and run update-database command.

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1 Comment

I just ran the update-database command then retried my add-migration command and it worked
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I had the same problems and was only able to resolve it running Add-Migration 'MigrationName' -Force

With -Force being the important part.

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My local database did not have the __MigrationHistory populated, or existing. I manually created the table, and then migrated the data in that table from PROD to my local database. This caused VS to think the migrations had been applied (which they had been).

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i had the same problem, i merged my live DB into production but therefore the migration history was lost.
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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.

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I had a simpler problem. VS erroneously reported this error when I had a VPN connection to a client's site connected on my workstation. The problem was that the DBMS security was set to accept requests only from my real local IP. Simply turning off the VPN resolved the problem.

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For me, i deleted the migration file(in your case "201203170856167_left") from Migrations folder, and then ran the below command in Package Manager console

Add-Migration <Parameter>
Update-Database
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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!

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1 Comment

I found this answer helpful. Even though I did not renamed my project, i was facing this issue. My problem was i was having a duplicate entry in __MigrationHistory with different ContextKeys. I deleted the redundant one and the issue was resolved.
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I've just seen this and it was because the SQL login account (used in the connection string) had 'Enforce password expiration' set in SQL Server Management Studio, and the password had expired! Hence it couldn't connect to the database to see existing migrations!

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Scenario

  • I am working in a branch in which I created a new DB migration.
  • I am ready to update from master, but master has a recent DB migration, too.
  • I delete my branch's db migration to prevent conflicts.
  • I "update from master".

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.

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I also came across this issue. It came when I created new DB and I had pending changes for my code-first DB migration then I tried to run "Update-Database" command. Solution : Run "Add-Migration -MigrationName" command to create new migration for new DB. Then run "Update-Database" command.

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I had this problem too for a database that I knew was up to date when running Add-Migration. Solved by simply running the Add-Migration command a second time. Suspect a connectivity issue, as suggested by Robin Dorbell above.

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In my scenario The database name was case sensitve when running the command. as soon as made the connectionstring exactly the same as what was in db, it worked fine
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That was happened when i suddenly renamed class of old migration that already exist in db. I checked VCS history, determined that and renamed back. All worked afterwards.

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I did another way. I droped database entirely and run "update-database" again in vs.

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This does not provide a viable fix; valid migration retains existing structure.
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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.

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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.

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In my case, just changed the startup project to the one that contains my migrations folder, also make sure that you selected the same project in the package console manager.

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I had the wrong database name. Instead of not found error it gave me every migration script

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-1

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.

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