The model backing the Database context has changed since the database was created

Question

The error message        The model backing the  AddressBook  context has changed since the database was created   Either manually delete update the database  or call Database SetInitializer with an IDatabaseInitializer instance   For example  the RecreateDatabaseIfModelChanges strategy will automatically delete and recreate the database  and optionally seed it with new data     I am trying to use the code-first feature and following is what I wrote   var modelBuilder   new ModelBuilder    var model   modelBuilder CreateModel    using  AddressBook context   new AddressBook model         var contact   new Contact               ContactID   10000          FirstName    Brian           LastName    Lara           ModifiedDate   DateTime Now          AddDate   DateTime Now          Title    Mr               context contacts Add contact       int result   context SaveChanges        Console WriteLine  Result  -    result ToString         The context class   public class AddressBook   DbContext       public AddressBook               public AddressBook DbModel AddressBook            base AddressBook                   public DbSet lt Contact gt  contacts   get  set        public DbSet lt Address gt  Addresses   get  set        and the connection string    lt  xml version  1 0  encoding  utf-8    gt   lt configuration gt       lt connectionStrings gt       lt add name  AddressBook  providerName  System Data SqlClient             connectionString  Data Source MyMachine Initial Catalog AddressBook           Integrated Security True MultipleActiveResultSets True    gt       lt  connectionStrings gt   lt  configuration gt    So  the database name is  AddressBook  and the error happens when I trying to add the contact object to the context  Am I missing anything here

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Modify Global asax cs  including the Application Start event with   Database SetInitializer lt YourDatabaseContext gt    new DropCreateDatabaseIfModelChanges lt YourDatabaseContext gt

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I spent many days to solve this issue  analyzed many different posts and tried many options and finally fixed   This 2 projects in my solution using EF code first migrations    Console Application  DataModel  that mainly using as assembly which contains all my code first entities  DbContext  Mirgations and generic repository  I have included to this project separate empty local database file  in DataModel App Data folder  to be able generate migrations from Package Manager Console     WebApi  which references to DataModel project and uses local database file from WebApi App Data folder  that not included in project   I got this error when requested WebApi     My environment    Windows 8 1 x64 Visual Studio 2015 Professional with Update 1 all my projects targeted for  NET Framework 4 6 1 EntityFramework 6 1 3 from NuGet   Here I collected all the remarks you should pay attention and all conditions requirements which must be met  to avoid mentioned exception     You should use only one version of EntityFramework Nuget package for all projects in your solution  Database  created by running sequentially all migration scripts should have the same structure schema as you target database and correspond to entity model  Following 3 things must exactly correspond reflect match each other    Your all migration script up to last Current code first entity model state  DbContext  entities  Target database  Target database  mdf file  should be updated correspond up to last migration script  Verify that    MigrationHistory  table in your target database contains records for all migration scripts that you have  it means that all migration scripts was successfully applied to that database  I recommend you to use Visual Studio for generation correct code first entities and context that corresponds to your database  Project -  Add New Item -  ADO NET Entity Data Model -  Code First from database    Of course  as an alternative  if you have no database you can write manually model  code first entities and context  and then generate initial migration and database   Name of connection string e g  MyConnectionString in config file of startup project  Web config App config     lt configuration gt     lt connectionStrings gt       lt add name  MyConnectionString  connectionString       gt     lt  connectionStrings gt   lt configuration gt    should be equal to parameter passed in constructor of your DbContext    public partial class MyDbContext   DbContext        public MyDbContext            base  name MyConnectionString              Before using Package Manager Console  make sure that you are using correct database for update or generate migration and needed project is set as startup project of solution  For connect to database it will use connection string from that  config file  which in project  that is set as startup project   And the main  which fixed my issue  It is weird  but in my WebApi bin folder DataModel exe was old  not refreshed since last build  Since migrations was embedded in my assembly DataModel exe then my WebApi updated database using old mirgations  I was confused why after updating database in WebApi it not corresponds to latest migration script from DataModel  Following code automatically creates if not exists  or updates to latest migration local database in my WebApi App Data folder       public class WebApiApplication   System Web HttpApplication             protected void Application Start                       Database SetInitializer new MigrateDatabaseToLatestVersion lt ODS DbContext  Configuration gt                        I tried clean and rebuild solution but it did not help  than I completely removed bin and obj folders from WebApi  deleted database files from WebApi App Data  built  restarted WebApi  made request to it  it created correct database - lazy initialization  using lines above   which corresponds to latest migration and exception didn t appear more  So  this may fix your problem    remove manually bin  obj folders from your startup project  which generates updates your database  build your startup project or better clean and rebuild all you solution  recreate database by starting project  will execute lines above  or use Package Manager Console  update-database  command   manually check whether generated db and   MirgationHistory corresponds to latest migration script

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After some research on this topic  I found that the error is occured basically if you have an instance of db created previously on your local sql server express  So whenever you have updates on db and try to update the db run some code on db without running Update Database command using Package Manager Console  first of all  you have to delete previous db on our local sql express manually    Also  this solution works unless you have AutomaticMigrationsEnabled   false in your Configuration    If you work with a version control system  git svn etc   and some other developers update db objects in production phase then this error rises whenever you update your code base and run the application    As stated above  there are some solutions for this on code base  However  this is the most practical one for some cases

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This fix no longer works after CTP5   You have to do Database SetInitializer lt YourContext gt  null

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Try using  Database SetInitializer which belongs to using System Data Entity   In Global asax   protected void Application Start         Database SetInitializer new DropCreateDatabaseIfModelChanges lt yourContext gt          This will create new database everytime your model is changed But your database would be empty In order to fill it with dummy data you can use Seeding  Which you can implement as     Seeding     protected void Application Start         Database SetInitializer new AddressBookInitializer                     ----rest code---   public class AddressBookInitializer   DropCreateDatabaseIfModelChanges lt AddressBook gt        protected override void Seed AddressBook context                context yourmodel Add                                 base Seed context

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I am reading the Pro ASP NET MVC 4 book as well  and ran into the same problem you were having   For me  I started having the problem after making the changes prescribed in the  Adding Model Validation  section of the book   The way I resolved the problem is by moving my database from the localdb to the full-blown SQL Server 2012 server    BTW  I know that I am lucky I could switch to the full-blown version  so don t hate me   -     There must be something with the communication to the db that is causing the problem

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For Entity Framework 5 0 0 0 - 6 1 3   You DO indeed want to do the following   1  using System Data Entity    to startup file  console app -- gt  Program cs   mvc -- gt  global asax 2  Database SetInitializer lt YourDatabaseContext gt  null     Yes  Matt Frear is correct  UPDATE -EDIT    Caveat is that I agree with others in that instead of adding this code to global asax added to your DbContext class  protected override void OnModelCreating DbModelBuilder modelBuilder           other code      Database SetInitializer lt YOURContext gt  null          more code here      As others mentioned this also is good for handling the unit testing   Currently I am using this with Entity Framework 6 1 3    net 4 6 1  I will come back to provide a CORE snippet in the near future

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Here s some information from Scott Gu s Blog posted by Jeff on what s actually taking place      For those who are seeing this exception        The model backing the  Production  context has changed since the   database was created  Either manually delete update the database  or   call Database SetInitializer with an IDatabaseInitializer instance        Here is what is going on and what to do about it       When a model is first created  we run a DatabaseInitializer to do   things like create the database if it s not there or add seed data    The default DatabaseInitializer tries to compare the database schema   needed to use the model with a hash of the schema stored in an   EdmMetadata table that is created with a database  when Code First is   the one creating the database   Existing databases won   t have the   EdmMetadata table and so won   t have the hash   and the implementation   today will throw if that table is missing  We ll work on changing this   behavior before we ship the fial version since it is the default    Until then  existing databases do not generally need any database   initializer so it can be turned off for your context type by calling   Database SetInitializer lt YourDbContext gt  null         Jeff

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It s weird  but all answers here were useless for me   For me worked initializer   MigrateDatabaseToLatestVersion  Here s my solution  I know  it can be much simplier  but it s how I use it    class MyDbMigrateToLatest   MigrateDatabaseToLatestVersion lt MyDbContext  Configuration gt       public class MyDbContext  DbContext       public MyDbContext     base  DbName                 SetInitializer               public MyDbContext string connString    base connString                SetInitializer               private static void SetInitializer                 if  ConfigurationManager AppSettings  RebuildDatabaseOnStart       true               Database SetInitializer new MyDbInitializerForTesting             else             Database SetInitializer new MyDbMigrateToLatest              public sealed class Configuration   DbMigrationsConfiguration lt MyDbContext gt        public Configuration                 AutomaticMigrationsEnabled   true             protected override void Seed MyDbContext context                   Whatever           MyDbInitializerForTesting just inherits from DropCreateDatabaseAlways so in some specific case  testing   whole database is rebuilded  Otherwise it s migrated to latest version   My source  https   msdn microsoft com en-us data jj591621 aspx specific

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Now it s   protected override void OnModelCreating DbModelBuilder modelBuilder        Database SetInitializer lt YourDbContext gt  null       base OnModelCreating modelBuilder       in your YourDbContext cs file

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Create custom context initializer   public class MyDbContextInitializer   MigrateDatabaseToLatestVersion lt MyDbContext  Migrations Configuration gt        public override void InitializeDatabase MyDbContext context                bool exists   context Database Exists             base InitializeDatabase context            if   exists                                 MyDbSeed Seed context                              Note that Migrations Configuration is a class generating by migration command line in Package Manager Console  You may need to change internal to public modifier of the Migrations Configuration class   And register it from your OmModelCreating   public partial class MyDbContext   DbContext        protected override void OnModelCreating DbModelBuilder modelBuilder                Database SetInitializer lt MyDbContext gt  new MyDbContextInitializer                other code for creating model

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Here I want to share another method that prevent the error of model backing when context changed is   1  Open your DbContext File  2  Add namespace using Microsoft AspNet Identity EntityFramework   3   public MyDbContext     base  name MyDbContext                         Database SetInitializer new        DropCreateDatabaseAlways

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Just run the followng sql command in SQL Server Management Studio   delete FROM  dbo     MigrationHistory

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I had the same problem when we used one database for two applications  Setting disableDatabaseInitialization  true  in context type section works for me    lt entityFramework gt   lt providers gt     lt provider invariantName  System Data SqlClient  type  System Data Entity SqlServer SqlProviderServices  EntityFramework SqlServer    gt   lt  providers gt   lt contexts gt     lt context type  PreferencesContext  Preferences  disableDatabaseInitialization  true  gt       lt databaseInitializer type  System Data Entity MigrateDatabaseToLatestVersion 2  PreferencesContext  Preferences    Migrations Configuration  Preferences    EntityFramework    gt     lt  context gt   lt  contexts gt      See more details https   msdn microsoft com en-us data jj556606 aspx

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Just in case someone has the same scenario as mine   I have database first EF and at the same time using the asp net identity  so I have two connectionStrings in my webconfig  and there is no problem with that  It happened that I created run the scripts to generate manually the asp net identity tables which I should not    so DROP first all the asp net identity tables created by you manually from scripts   DROP TABLE   MigrationHistory DROP TABLE AspNetRoles DROP TABLE AspNetUserClaims DROP TABLE AspNetUserLogins DROP TABLE AspNetUserRoles DROP TABLE AspNetUsers

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Just found out the answer and thought of updating here  Just need to do the following   public class AddressBook  DbContext      protected override void OnModelCreating ModelBuilder modelBuilder           modelBuilder IncludeMetadataInDatabase   false

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For me  with the upgrade to 4 3 1  I just truncate the EdmMetaData table or just delete it outright

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I had this issue and it turned out that one project was pointing to SQLExpress but the one with the problem was pointing to LocalDb   in their respective web config   Silly oversight but worth noting here in case anyone else is troubleshooting this issue

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Or you can put this line in your Global asax cs file under Application Start     System Data Entity Database SetInitializer new System Data Entity DropCreateDatabaseIfModelChanges lt ProjectName Path Context gt        Make sure to change ProjectName Path Context to your namespace and context  If using code first this will delete and create a new database whenever any changes are made to the schema

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I had the same issue - re-adding the migration and updating the database didn t work and none of the answers above seemed right  Then inspiration hit me - I m using multiple tiers  one web  one data  and one business   The data layer has the context and all the models  The web layer never threw this exception - it was the business layer  which I set as console application for testing and debugging   Turns out the business layer wasn t using the right connection string to get the db and make the context  So I added the connection string to the app config of the business layer  and the data layer  and viola it works  Putting this here for others who may encounter the same issue

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Check this following steps    Database SetInitializer null      -- in Global asax cs   2            your Context class name should match with   check it

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None of these solutions would work for us  other than disabling the schema checking altogether   In the end we had a miss-match in our version of Newtonsoft json  Our AppConfig did not get updated correctly    lt dependentAssembly gt      lt assemblyIdentity name  Newtonsoft Json  publicKeyToken  30ad4fe6b2a6aeed  culture  neutral    gt       lt bindingRedirect oldVersion  0 0 0 0-7 0 0 0  newVersion  7 0 0 0    gt     lt  dependentAssembly gt    The solution was to correct the assembly version to the one we were actually deploying   lt dependentAssembly gt      lt assemblyIdentity name  Newtonsoft Json  publicKeyToken  30ad4fe6b2a6aeed  culture  neutral    gt       lt bindingRedirect oldVersion  0 0 0 0-7 0 0 0  newVersion  10 0 0 0    gt     lt  dependentAssembly gt

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For VB NET developers   Add the following line to the Glabal asax vb file  at the end of method Application Start    Database SetInitializer Of ApplicationDbContext  Nothing    Change ApplicationDbContext to your specific Db context

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This error can indicate an issue with your connection string and whether your connection string name matches the Database context declaration   I had this error because I had named the local database wrongly  silly mistake  and the name of the connection string in web config of  DefaultConnection  did not match the MyDbContext i e    public MyDbContext    base  DefaultConnection         lt connectionStrings gt       lt add name  DefaultConnection         lt  connectionStrings gt

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Good suggestion  however  nt so accurate in all cases  I figure one out  Please you need to make sure you run   enable-migrations  using PM windows in Visual Studio  and Migration folder would be added to you project   Make sure the two c  class files added to the folder on will contain all your models and their respective properties   If you have all that build the solution  and publis for deployment   The logic is that the existing metadata cannot be overwritten because your application has no metadata to replace the current  As a result you are getting this error  The model backing the  context has changed since the database was created

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It means that there were some changes on the context which have not been executed  Please run Add-Migration first to generate the changes that we have done  the changes that we might not aware  And then run Update-Database

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I use the Database CompatibleWithModel method  available in EF5  to test if the model and DB match before I use it  I call this method just after creating the context                test the context to see if the model is out of sync with the db            if   MyContext Database CompatibleWithModel true                            delete the old version of the database                if  File Exists databaseFileName                   File Delete databaseFileName               MyContext Database Initialize true                   re-populate database

[.net] The model backing the <Database> context has changed since the database was created

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