The type or namespace name Entity does not exist in the namespace System Data

Question

I m using WS class and it gave me error when I run the application   The type or namespace name  Entity  does not exist in the namespace  System Data     I have a reference to the System Data  and to System Data Entity  But no changes  I keep getting the error  I have also in the web config the line     lt compilation debug   true  targetFramework  4 0   gt

User · Answer

My solution was simple  I was actually having this error when checked out a repo from a svn server  I took following steps to remove error   Cleaned solution Went to nuget package manager and uninstalled the entity framework  Removed DataModel and its  cs components  Shutdown the VS and opened again  Installed Entity Framework and Recreated entity model  Check if there is any files needed  Include in the solution   It worked like a charm

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I noticed that in the csproj the framework entity had hintpath like   lt HintPath gt                   Users  myusername    I had this in the nuget config file     lt config gt    lt add key  repositoryPath  value     lib    gt    lt  config gt    a  I removed the above lines  b  uninstalled the framework entity package  c  THEN CLOSED THE solution and reopened it  d  reinstalled the framework   It fixed my issue

User · Answer

Thanks every body   I found the solution  not that I understand why but I tried this and it worked  I just had to add a reference to  System Data Entity Design and don t have to write any using in the code  Thanks

User · Answer

Make sure you have the EntityFramework Nuget package installed for your project   From  TonyDing s answer      Right-click on the Solution from the Visual Studio Solution Explorer   click the Manage Nuget packages for solution and install the   EntityFramework   Once it is installed  I still had the error  but then did a reinstall per  papergodzilla s comment      Update-Package -reinstall   and it resolved my issue  Do this in the Package Manager Console  View   Other windows   Package Manager Console   Now everything is good

User · Answer

tried reinstall - no luck  i had to refresh a table in my model before it would find Entity

User · Answer

If you re using a database-first approach   Before uninstalling   reinstalling Entity Framework  first try simply adding another table   stored procedure to your model  assuming there are any currently unmapped   That fixed the issue for me  Of course if you don t need the resource mapped then just delete it from the model afterwards  But it looks like a force-regeneration of the edmx did the trick

User · Answer

I found the root cause is when you install the nuget packages through the UI the scripts won t run sometimes  So I d recommend open Output view while you do that  If you don t see the license agreement window when installing Nuget  there is a better change your IDE isn t doing the job right  So that s why a restart  cleanup and rebuild helps   PS  That adding anything under System Data Entity   helps because  that triggers the Nuget installer to work properly  But this I found a quite unreliable way    So just watch the output window  you MUST see something like a successful nuget installation message at the end  Most the time when there an issue  Nuget installer won t even kick off  That s when your restart of IDE is going to help   When things go well  Nuget package manager and IDE  I used Installer term above  would do the change  compile the solution and keep you happy  But when its not give a little help by restarting IDE and watching that Output window

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Most of the answers here seem to lack awareness of the namespace change that happened between EF 6 2 and 6 3   I was intentionally upgrading from EF 6 1 to 6 3 to be able to target  NET Standard 2 1  However  I accidentally used  NET Standard 2 0 for the new target in my lib and then got the The type or namespace name  Entity  does not exist in the namespace  System Data   This GH issue comment gave me the clue I needed to fix  I changed my lib target to  NET Standard 2 1 and the project compiled  No re-installs  uninstalls  or restarts were required

User · Answer

If you are using EF version more than 6 x   then see if you have installed the entity framework nuget package in every project of your solution  You might have installed Ef but not in that particular project which you are working on

User · Answer

Hi this post is very misleading  if your reading this 2 years on   With using EF6 and  net 4 5 1 in VS 2013 I have had to reference the following to get this to work  using System Data Entity Core EntityClient    a little different to before   this is more of a FYI for people that come here for help on newer problems than a answer to the original question

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I will add my answer to cover all cases   My solution was unistalling EntityFramework from NuGet Package Manager and then I was prompted to restart Visual Studio because it couldn t  finalize the uninstall    I restarted Visual Studio and reinstalled EntityFramework then my problem was solved   Hope this helps someone

User · Answer

You need to install Entity framework by right click on your VS solution and click Manage NuGet Package solution and search there Entity framework  After installation the issue will be solved

User · Answer

I installed EntityFramework 6 2 instead of 6 3 and it worked   Perhaps it is the  NetCoreApp v2 1 or  NETFramework v4 6 1

User · Answer

I had to reference System Data DataSetExtensions  which seems completely illogical

User · Answer

I had just updated my Entity framework to version 6 in my Visual studio 2013 through NugetPackage and add following References   System Data Entity  System Data Entity Design  System Data Linq   by right clicking on references- Add references in my project  Now delete my previously created Entity model and recreate it again Built solution  Now It works fine for me

User · Answer

Right-click on the Solution from the Visual Studio Solution Explorer click the Manage Nuget packages for solution and install the EntityFramework

User · Answer

I had entity framework 6 1 3  upgraded  well  more downgraded in NuGet  to 6 1 2  Worked

User · Answer

I had the same errors    I added System Data Entity Repository from Nuget Packages and the errors disappears    Hope it wil help

User · Answer

It s helped me  I uninstalled EF  restarted VS and I added  using    using System Data Entity  using System Data Entity Core Objects  using System Data Entity Infrastructure

User · Answer

I just had the same error with Visual Studio 2013 and EF6  I had to use a NewGet packed Entity Framework and done the job perfectly

User · Answer

I had to refresh my DBModel  That solved it

[c#] The type or namespace name 'Entity' does not exist in the namespace 'System.Data'

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