The type or namespace name DbContext could not be found

Question

I am VERY new to ASP NET MVC  3  and am having a hard time resolving a build error in Visual Studio   The type or namespace name  DbContext  could not be found  are you missing a using directive or an assembly reference    using System  using System Collections Generic  using System Linq  using System Web  using System ComponentModel DataAnnotations  using System Data Entity   namespace MyProjectName Models          public class MachineModel                  name          Required           Display Name    Nom de la machine            public string Name   get  set                IP          Required           RegularExpression         25 0-5  2 0-4  0-9   01   0-9  0-9       3    25 0-5  2 0-4  0-9   01   0-9  0-9                 ErrorMessage    Donnez une adresse IPv4 valide              Display Name    Adresse IP de la machine            public string IP   get  set               public class MachineDbContext   DbContext               public DbSet lt MachineModel gt  Machines  get  set              The two errors I am getting are    The type or namespace name  DbContext  could not be found  are you missing a using directive or an assembly reference    The type or namespace name  DbSet  could not be found  are you missing a using directive or an assembly reference     What am I missing

User · Accepted Answer

I had the same issue  Turns out  you need the EntityFramework dll reference  and not System Data Entity    I just pulled it from the MvcMusicStore application which you can download from  http   mvcmusicstore codeplex com   It s also a useful example of how to use entity framework code-first with MVC

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There might be a case where you reference everything you need to and you can even Go to Definition by pressing F12 on DbContext class which takes you to System Data Entity namespace but you still get this nasty compiler warning  Make sure that the Target Framework of your project and that of the Entity Framework version you are using match  Go to Project- Properties- Application Tab  Change the Target Framework can t exactly say to which one  trial and error will help    Just my two cents

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I had to first uninstall EntityFramework Uninstall-package EntityFramework  not case sensitive apparently    then install it again Install-package EntityFramework   via the PM Console

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I had the same problem using VS2010   I know this isn t really an answer  I just thought it might help someone  I resolved it by using the fully qualified name for DBContext   Instead of  public class MachineDbContext   DbContext   I used   public class MachineDbContext   System Data Entity DbContext   and rebuilt the project  Suddenly VS was happy  and I was even able to remove the fully qualified name  and just use DBContext

User · Answer

having referenced entityframework dll both system data entity worked

User · Answer

i had the same problem I had to rewrite  DBContext  after adding reference to entityframework and it resolved the problem  its means that Visual studio was not able to recognize the class automatically and waited for it to be re-typed   so its best to add reference first and then implement code   VS 2013 - ultimate used

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This happened to me when I branched code  To fix it I right-clicked my project in Visual Studio  chose manage Nu-get packages  uninstalled EntityFramework  then re-installed it  Problem solved

User · Answer

1  Uninstalling Entity Framework from All projects  2  Restart Visual Studio  3  Reinstalling to all required projects   and it started working

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Just a quick note  It is DbContext  not DBContext  i e  with a lowercase  B   I discovered this because I had the same problem while intelesense was not working until I tried typing the full name space System Data Entity    and name and finally it suggested the lowercase  b  option -  System Data Entity DbContext

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I also get irritated from this issue many times and finally find the solution Go to edmx file- Update Model from Database- Refresh- Finish  Clean Solution- Rebuild Solution

User · Answer

Visual Studio Express SP1 Right click in Solution Explorer   References   Add Library Package Reference   EntityFramework

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For step-by-step instructions  see this new MVC   EF tutorial series  http   www asp net entity-framework tutorials creating-an-entity-framework-data-model-for-an-asp-net-mvc-application The tutorial assumes you have installed the latest MVC 3 Tools Update and provides a link in case you haven t

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Right click your reference and go to manage NuGet packages  then choose online all  then NuGet package source in the search textbox type Entity Framework and install it

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I had the same problem  I have VS2010 express     Note  If you see this problem try checking references to EntityFramework dll    May be it is missing    The following resolved it for me   I installed latest MVC 3 Tools Update then I installed EntityFramework 4 1   or using  NUGet ie  from with Visual Studio 2010 Express  Tools- Library Package Manager -  Add library Package reference -  Select Online -  EntityFramework     Strangely that didnt work  So i had to manually add a reference to  EntityFramework dll  try doing a  search for the dll   may be here  C  Program Files  x86  Reference Assemblies Microsoft Framework NETFramework v4 0      If you already have it  just add a   net  reference   Note  If you use NuGet  it creates a folder  packages  along side your Solution directory  You will find the  EntityFramework 4 1 10331 0  folder inside it Within  Libs  folder you will find  EntityFramework dll     Add reference to it using Browse tab and select the above dll

User · Answer

I had the same issue    Installing the EF from Package Manager Console worked for me  the command was  Install-Package EntityFramework

User · Answer

I had this problem  read the above answer and download the entityframework ddl but found that it is alreadt referenced  So I added the namespace and problem was solved  using System Data Entity   I am using Visual Studio 2010  SP1 installed

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I just had this issue and none of the other solutions worked for me  I m using Visual Studio 2010 and I have two projects in my solution  UIProject and DataAccessProject  The UIProject has a reference to the DataAccessProject   My UIProject was targeting the  Net Framework 4 but my DataAccessProject was targeting the  Net Framework 3 5 for some reason     I changed both projects to target  Net Framework 4  Uninstalled then re-installed the Entity Framework NuGet Package    Problems solved  Now I have references to both EntityFramework and System Data Entity

User · Answer

This helps really handy    Select the ProjectNAme project in Solution Explorer  From the Tools Menu  choose Library Package Manager which has a sub-menu  From the sub-menu choose Package Manager Console  At the console   s PM prompt type install-package EntityFramework then hit enter

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you can try on package manager console  PM  EntityFrameWork enable-migrations

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Use CTP5 instead it is newer version with some changes in API  You have to add reference to EntityFramework dll which is installed in CTP directory - default is  c  Program Files Microsoft ADO NET Entity Framework Feature CTP5 Binaries EntityFramework dll for 32bit system  On 64bit system it will be placed in Program Files  x86

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You need to reference the System Data Entity assembly in your project  or install the EntityFramework NuGet package  which will setup everything for you

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Your project unable to resolve EntityFramework classes until you not added it in your project   For adding EntityFramework support you have to follow this steps  Tools- Nuget Package Manager - Manage Nuget package for solution browse EntityFramework It shows latest stable EntityFramework version  currently 6 1 3 is latest version Install it for the selected project

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As alternative way you can go HERE - instruction how to install any required dll   Or you can download NuGet and manage it from VS

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Download http   www dll-found com download e EntityFramework dll  Paste it in  for x86    C  Program Files  x86  Reference Assemblies Microsoft Framework  NETFramework v4 0    Then Right click on project -  add reference -  select EntityFramework  Bingo

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I had the same error but the problem was just an accidental problem with my model   I accidentaly put     public class MyModelDBContext   Context    public DBSet lt MyModel gt  MyModels   get  set           inside of the model class

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I am using Visual Studio 2010 express and adding a reference to C  Program Files Microsoft ADO NET Entity Framework 4 1 Binaries EntityFramework dll solved the problem

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Like the others have suggested    Add the correct references and directives  But it still doesn t work  Maybe you have the same problem I did    Have a look below and see if you can tell me what is wrong   public class PanelLengthContext   DBContext              Make sure the class name is not misspelt -  case sensitivity     DbContext is the correct spelling  this is how it should look  check the spelling  don t waste 20 min of your life like i did  public class PanelLengthContext   DbContext      HTH

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If your compiler doesn t recognize   System Data Entity Infrastructure DbContext DbSet et alii    make sure   you have Entity Framework 4 1 installed on your machine  in your  csproj file  you have the following reference   lt Reference Include  EntityFramework  Version 4 1 0 0  Culture neutral  PublicKeyToken b77a5c561934e089  processorArchitecture MSIL    gt   within the element   lt ItemGroup gt         lt  ItemGroup gt   that houses references to other assemblies

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I have the same issue as you  I m unable to implement it in the Controller class while it works when I put it in the model class  Add these codes on the top of your controller class   using TimeSheetManagementSystem Data   using Microsoft Extensions Configuration   using Microsoft AspNetCore Identity EntityFrameworkCore   using Microsoft EntityFrameworkCore   using Newtonsoft Json

[asp.net-mvc] The type or namespace name 'DbContext' could not be found

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