The type or namespace name does not exist in the namespace System Web Mvc

Question

Buiding MVC3 solution went well but have got an error in browser   Compiler Error Message  CS0234  The type or namespace name  Html  does not exist in the namespace  System Web Mvc   are you missing an assembly reference    Source Error  Line 25           lt add namespace  System Web Mvc    gt  Line 26           lt  -- lt add namespace  System Web Mvc Ajax    gt -- gt  Line 27           lt add namespace  System Web Mvc Html    gt  Line 28           lt add namespace  System Web Routing    gt  Line 29           lt add namespace  System Web WebPages    gt    I have installed packets for the solution with NuGet and set up for all projects MVC3  Does MVC3 include libraries System Web Mvc Ajax   System Web Mvc Html and others  Why am I getting the error     In References folder  I have System Web Mvc  Runtime version  v4 0 30319   Version  3 0 0 0     Web config   lt  xml version  1 0  encoding  utf-8   gt   lt  --   For more information on how to configure your ASP NET application  please visit   http   go microsoft com fwlink  LinkId 152368   -- gt   lt configuration gt     lt configSections gt       lt  -- For more information on Entity Framework configuration  visit http   go microsoft com fwlink  LinkID 237468 -- gt       lt section name  entityFramework  type  System Data Entity Internal ConfigFile EntityFrameworkSection  EntityFramework  Version 5 0 0 0  Culture neutral  PublicKeyToken b77a5c561934e089  requirePermission  false    gt     lt  configSections gt     lt appSettings gt       lt add key  aspnet UseTaskFriendlySynchronizationContext  value  true    gt       lt add key  webpages Version  value  1 0 0 0    gt       lt add key  ClientValidationEnabled  value  true    gt       lt add key  UnobtrusiveJavaScriptEnabled  value  true    gt     lt  appSettings gt     lt system web gt       lt compilation debug  true  targetFramework  4 5    gt       lt authentication mode  Forms  gt         lt forms loginUrl    Account LogOn  timeout  2880    gt       lt  authentication gt       lt pages gt         lt namespaces gt           lt add namespace  System Web Helpers    gt           lt add namespace  System Web Mvc    gt           lt add namespace  System Web Mvc Ajax    gt           lt add namespace  System Web Mvc Html    gt           lt add namespace  System Web Routing    gt           lt add namespace  System Web WebPages    gt         lt  namespaces gt       lt  pages gt       lt httpRuntime targetFramework  4 5  encoderType  System Web Security AntiXss AntiXssEncoder  System Web  Version 4 0 0 0  Culture neutral  PublicKeyToken b03f5f7f11d50a3a    gt       lt machineKey compatibilityMode  Framework45    gt       lt profile defaultProvider  DefaultProfileProvider  gt         lt providers gt           lt add name  DefaultProfileProvider  type  System Web Providers DefaultProfileProvider  System Web Providers  Version 1 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35  connectionStringName  DefaultConnection  applicationName       gt         lt  providers gt       lt  profile gt       lt membership defaultProvider  DefaultMembershipProvider  gt         lt providers gt           lt add name  DefaultMembershipProvider  type  System Web Providers DefaultMembershipProvider  System Web Providers  Version 1 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35  connectionStringName  DefaultConnection  enablePasswordRetrieval  false  enablePasswordReset  true  requiresQuestionAndAnswer  false  requiresUniqueEmail  false  maxInvalidPasswordAttempts  5  minRequiredPasswordLength  6  minRequiredNonalphanumericCharacters  0  passwordAttemptWindow  10  applicationName       gt         lt  providers gt       lt  membership gt       lt roleManager defaultProvider  DefaultRoleProvider  gt         lt providers gt           lt add name  DefaultRoleProvider  type  System Web Providers DefaultRoleProvider  System Web Providers  Version 1 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35  connectionStringName  DefaultConnection  applicationName       gt         lt  providers gt       lt  roleManager gt       lt sessionState mode  InProc  customProvider  DefaultSessionProvider  gt         lt providers gt           lt add name  DefaultSessionProvider  type  System Web Providers DefaultSessionStateProvider  System Web Providers  Version 1 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35  connectionStringName  DefaultConnection    gt         lt  providers gt       lt  sessionState gt     lt  system web gt     lt system webServer gt       lt validation validateIntegratedModeConfiguration  false    gt     lt  system webServer gt     lt runtime gt       lt assemblyBinding xmlns  urn schemas-microsoft-com asm v1  gt         lt dependentAssembly gt           lt assemblyIdentity name  System Web Mvc  publicKeyToken  31bf3856ad364e35    gt           lt bindingRedirect oldVersion  1 0 0 0-2 0 0 0  newVersion  3 0 0 0    gt         lt  dependentAssembly gt       lt  assemblyBinding gt     lt  runtime gt     lt entityFramework gt       lt defaultConnectionFactory type  System Data Entity Infrastructure SqlConnectionFactory  EntityFramework    gt     lt  entityFramework gt     lt connectionStrings gt       lt add name  EFDbContext  connectionString  Data Source   SQLEXPRESS Initial Catalog SportStore Integrated Security True Pooling False   providerName  System Data SqlClient    gt     lt  connectionStrings gt   lt  configuration gt    MSDN the System Web Mvc namespace  file packages config    lt  xml version  1 0  encoding  utf-8   gt   lt packages gt     lt package id  EntityFramework  version  5 0 0-rc    gt     lt package id  jQuery  version  1 7 2    gt     lt package id  jQuery UI Combined  version  1 8 11    gt     lt package id  jQuery Validation  version  1 9    gt     lt package id  Microsoft AspNet Mvc  version  3 0 20105 1    gt     lt package id  Microsoft AspNet Providers Core  version  1 0    gt     lt package id  Microsoft AspNet Providers LocalDB  version  1 0    gt     lt package id  Microsoft AspNet Razor  version  1 0 20105 408    gt     lt package id  Microsoft AspNet WebPages  version  1 0 20105 408    gt     lt package id  Microsoft Web Infrastructure  version  1 0 0 0    gt     lt package id  Modernizr  version  2 0 6    gt     lt package id  Moq  version  4 0 10827    gt     lt package id  Ninject  version  3 0 1 10    gt   lt  packages gt

User · Answer

It s likely that setting your DLL to CopyLocal true or any of the other major fixes for this will fix your issue  but here is another edge-case that caught me for 20 minutes of wasted time   When you add your namespaces to your Views Web config  ensure they are cased correctly      lt system web webPages razor gt       lt host factoryType  System Web Mvc MvcWebRazorHostFactory  System Web Mvc  Version 5 2 3 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt       lt pages pageBaseType  System Web Mvc WebViewPage  gt         lt namespaces gt           lt add namespace  THE NameSpace    gt           lt add namespace  THE Namespace    gt         lt  namespaces gt       lt  pages gt     lt  system web webPages razor gt

User · Answer

I had the same problem  but in my case was originated by other factor  I write this to help other people with the same problem  I have a solutions with multiple projects  two of them work with the System Web Mvc  Normally our reference was pointing to external packages where we controlled the used version  For some reason one of the project reference goes to GAC and point to the GAC dll  version 4 0 0 1  and the program got the error   To correct it   Simple check if the references to System Web Mvc point to the same dll in the same directory path   I hope that help

User · Answer

if any of above not solves your problem just set properties of System Web Mvc dll to copy local ture   it will solves

User · Answer

I have deleted System Web dll from Bin frolder of my site

User · Answer

Running the following command in the nuget package manager fixed it for me   update-package microsoft aspnet mvc -reinstall

User · Answer

View and check the reference paths in your csproj   I had removed references to System Web Mvc  and others  and readded them to a custom path  C  Project OurWebReferences  However  after doing this  the reference path in the still csproj did not change   WAS   lt Reference Include  System Web Mvc  Version 4 0 0 1  Culture neutral  PublicKeyToken 31bf3856ad364e35  processorArchitecture MSIL  gt     lt SpecificVersion gt False lt  SpecificVersion gt     lt HintPath gt             OurWebProject bin Debug System Web Mvc dll lt  HintPath gt   lt  Reference gt    Changed to manually   lt Reference Include  System Web Mvc  Version 4 0 0 1  Culture neutral  PublicKeyToken 31bf3856ad364e35  processorArchitecture MSIL  gt     lt SpecificVersion gt False lt  SpecificVersion gt           lt HintPath gt             OurWebReferences System Web Mvc dll lt  HintPath gt   lt  Reference gt    Paths are an example only

User · Answer

I did something really stupid  and maybe you did too     I was trying to call System Web Mvc Html Partial   lt Partial Page gt     System Web Mvc Html is a namespace and not a class and I didn t read my error message so well  so I interpreted my error as the class Html does not exist in the namespace System Web Mvc and that s how I ended up here  stupid I know     All I needed to do was add a using statement  using System Web Mvc Html to my page and then  Html Partial worked as expected

User · Answer

I had the same problem  none of the solutions worked for me  Finally I removed the System Web MVC and added again Then everything was back to normal and my problem solved

User · Answer

You need to update MVC    Go to Tools -  NuGet Package Manager -  Manage NuGet Packages for Solution Click on  Updates  Update  Microsoft ASP NET MVC  Rebuild Solution

User · Answer

For me  the solution was to ensure all projects were building for the same CPU - in my case x86

User · Answer

For whatever reason  TWO of my solutions have web projects that spontaneously uninstalled asp net MVC somehow  I installed it from Nuget and now they both work again  This happened after a recent batch of windows updates that included  net framework updates for the version I was using  4 5 1    Edit  From the  Net Web Development and Tools Blog   Microsoft Asp Net MVC Security Update MS14-059 broke my build

User · Answer

I had the same issue  but none of the above worked for me  They did put me in to the right direction though   For example when I set the  Copy Local  to  true  for System Web Mvc reference  it automatically sets it back to False   I have multiple projects which  depend on the System Web Mvc reference in my solution  but only one caused this problem   In VS 2012 this reference is labeled with the yellow attention triangle   Find this reference    remove it    re-add it  That fixed it for me  Hope this helps

User · Answer

I downloaded an mvc 5 project and the offending issue pointing at     lt add namespace  System Web Mvc Ajax    gt      With this error message   CS0234  The type or namespace name  Ajax  does not exist in the namespace  System Web Mvc   are you missing an assembly reference     --    in which I came to this webpage and tried a clean and a few things above etc        What worked for me was just to   Manage Nuget and Update all the packages   Then it worked fine

User · Answer

I have a project that does this whenever I build with the View open   As soon as I closed the view  the error goes away and the build succeeds   Very strange

User · Answer

This one normally catches me when I run from IIS and the app pool for the default site is set to  NET version 2 0  When using IIS from visual studio it creates a virtual directory but still runs under the default site s app pool  If using the build in web server  right click on your web project  go to properties and make sure you re running it under the right version of  NET  On IIS check the  NET version on your app pool   Following on from my last comment about how the project was created - are you correctly including the assemblies  as below  taken from the default web config file generated by the MVC3 project template in VS10     lt compilation debug  true  targetFramework  4 0  gt         lt assemblies gt           lt add assembly  System Web Abstractions  Version 4 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt           lt add assembly  System Web Helpers  Version 1 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt           lt add assembly  System Web Routing  Version 4 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt           lt add assembly  System Web Mvc  Version 3 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt           lt add assembly  System Web WebPages  Version 1 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt         lt  assemblies gt   lt  compilation gt

User · Answer

Copy Local   True was solve for one of my projects  But in another project  I get the same error  tried to set Copy Local   true  but it not solve my problem  Changing the Target framework from 4 5 1 to 4 5 in Project Properties Helped with this

User · Answer

Clean your solution and then set the property of those files to Copy Local   True   To set the Copy Local property to True or False  In Solution Explorer  click the Show All Files button to display the References node    Open the References node for the project  Right-click a reference in the References list  and click Properties  The properties associated with that reference appear in a list in the Properties window  In the Properties window  change the Copy Local property to True or False

User · Answer

This answer is rather late given the question date  but someone may find it useful   None of the above solutions worked for me in Visual Studio 2012 on a local project  Net Framework 4 5 MVC 4  For context  I was following a tutorial on creating a barebones Web Api on CodeProject  http   www codeproject com Articles 615805 Creating-a-Clean-Minimal-Footprint-ASP-NET-WebAPI  when I ran into this problem   What did work for me was explicitly adding  System Web Mvc  to my application s references  even though the application already did reference  System Web

User · Answer

I had this problem  setting copy local on and off etc did not work  The project was not using nuget so fixes around that were out of the question also   The fix for me was to install MVC 3  which I did through the web platform installer     I suspect this will become more of a solution for people as the  net framework continues to advance and people don t have the older MVC stuff installed

User · Answer

I had the same problem - my scenario was that I was referencing the new System Web Mvc dll from a lib folder and I did not have  Copy Local  set to true   The application was then reverting back to the version in the GAC which didn t have the correct namespaces  Html  Ajax etc  in it and was giving me the run time error

User · Answer

Ok so a lot of people seem to be experiencing this issue  My problem was caused by references having paths to the bin folders of other projects  or referencing dlls from system folders  The project was about 6 years old and the previous developers had decided that this was the way they were going to reference their libraries    The solution was to go through every reference and check the paths  then remove the reference and add it using NuGet  For any package that wasn t on NuGet I created another folder alongside packages and put the dll in there in the same layout as NuGet would   I also had to go through the config files and make sure the correct version of the packages was being used  A long and painful process

User · Answer

My solution was under Manage Nuget Packages for Solution    -- I had umpteen updates to do for quite a few packages   Let me back up a half step and say that I screwed myself over because I moved the solution and projects from one folder to another    so things were already out of whack compared to where the projects thought things out to be  Everything moved over just fine  but apparently Nuget becomes confused unless you use a different approach than I did   Back to the solution    I simply went to Manage Nuget Packages for Solution       Updates    Microsoft and  NET and hit the Update All button   Everything was back to normal and happy

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

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