Could not load file or assembly System Web WebPages Razor Version 2 0 0 0

Question

I just upgraded packages in an MVC 3 project  ASP net 4   and now I am getting the following error message when accessing a page in that project      Server Error in   MyApplication  Application       Could not load file or assembly  System Web WebPages Razor    Version 2 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35  or   one of its dependencies  The located assembly s manifest definition   does not match the assembly reference   Exception from HRESULT    0x80131040   Description  An unhandled exception occurred during the   execution of the current web request  Please review the stack trace   for more information about the error and where it originated in the   code        Exception Details  System IO FileLoadException  Could not load file or   assembly  System Web WebPages Razor  Version 2 0 0 0  Culture neutral    PublicKeyToken 31bf3856ad364e35  or one of its dependencies  The   located assembly s manifest definition does not match the assembly   reference   Exception from HRESULT  0x80131040       Source Error        An unhandled exception was generated during the execution of the   current web request  Information regarding the origin and location of   the exception can be identified using the exception stack trace below       Assembly Load Trace  The following information can be helpful to   determine why the assembly  System Web WebPages Razor    Version 2 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35    could not be loaded           Pre-bind state information     LOG  User   IIS APPPOOL ASP NET v4 0 LOG  DisplayName   System Web WebPages Razor  Version 2 0 0 0    Culture neutral  PublicKeyToken 31bf3856ad364e35   Fully-specified    LOG  Appbase   file    C       LOG  Initial PrivatePath   C     bin   Calling assembly   Microsoft Web Helpers  Version 2 0 0 0    Culture neutral  PublicKeyToken 31bf3856ad364e35        LOG  This bind starts in default load context  LOG  Using application configuration file  C     web config LOG  Using host   configuration file    C  Windows Microsoft NET Framework64 v4 0 30319 aspnet config LOG    Using machine configuration file from   C  Windows Microsoft NET Framework64 v4 0 30319 config machine config    LOG  Post-policy reference  System Web WebPages Razor    Version 2 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35 LOG    Attempting download of new URL   file    C  Windows Microsoft NET Framework64 v4 0 30319 Temporary   ASP NET Files     cb62a7b2 327a0353 System Web WebPages Razor DLL    LOG  Attempting download of new URL   file    C  Windows Microsoft NET Framework64 v4 0 30319 Temporary   ASP NET   Files     cb62a7b2 327a0353 System Web WebPages Razor System Web WebPages Razor DLL    LOG  Attempting download of new URL   file    C  LeGroupeHtmSVN     UpDir Web bin System Web WebPages Razor DLL    WRN  Comparing the assembly name resulted in the mismatch  Major   Version ERR  Failed to complete setup of assembly  hr   0x80131040     Probing terminated         Stack Trace         FileLoadException  Could not load file or assembly    System Web WebPages Razor  Version 2 0 0 0  Culture neutral    PublicKeyToken 31bf3856ad364e35  or one of its dependencies  The   located assembly s manifest definition does not match the assembly   reference   Exception from HRESULT  0x80131040     Microsoft Web Helpers PreApplicationStartCode Start    0       InvalidOperationException  The pre-application start initialization   method Start on type Microsoft Web Helpers PreApplicationStartCode   threw an exception with the following error message  Could not load   file or assembly  System Web WebPages Razor  Version 2 0 0 0    Culture neutral  PublicKeyToken 31bf3856ad364e35  or one of its   dependencies  The located assembly s manifest definition does not   match the assembly reference   Exception from HRESULT  0x80131040      System Web Compilation BuildManager InvokePreStartInitMethods ICollection 1   methods   11711966   System Web Compilation BuildManager CallPreStartInitMethods    465   System Web Hosting HostingEnvironment Initialize ApplicationManager   appManager  IApplicationHost appHost  IConfigMapPathFactory   configMapPathFactory  HostingEnvironmentParameters hostingParameters    PolicyLevel policyLevel  Exception appDomainCreationException   1167       HttpException  0x80004005   The pre-application start initialization   method Start on type Microsoft Web Helpers PreApplicationStartCode   threw an exception with the following error message  Could not load   file or assembly  System Web WebPages Razor  Version 2 0 0 0    Culture neutral  PublicKeyToken 31bf3856ad364e35  or one of its   dependencies  The located assembly s manifest definition does not   match the assembly reference   Exception from HRESULT  0x80131040      System Web HttpRuntime FirstRequestInit HttpContext context   11700896   System Web HttpRuntime EnsureFirstRequestInit HttpContext context     141    System Web HttpRuntime ProcessRequestNotificationPrivate IIS7WorkerRequest   wr  HttpContext context   4869125      -------------------------------------------------------------------------------- Version Information  Microsoft  NET Framework Version 4 0 30319    ASP NET Version 4 0 30319 272   In my web config file  and in my application  I am referencing System Web WebPages Razor v1 0 0 0       lt dependentAssembly gt       lt assemblyIdentity name  System Web WebPages Razor  publicKeyToken  31bf3856ad364e35  culture  neutral    gt       lt bindingRedirect oldVersion  0 0 0 0-1 0 0 0  newVersion  1 0 0 0    gt     lt  dependentAssembly gt     I don t even know whether I could be using System Web WebPages Razor v2 0 0 0 with  Net 4   Now  how do I find out what is referencing System Web WebPages Razor v2 0 0 0

User · Answer

In some cases  just install web page 2 to resolve this  resolved with my case - deploy to local web page using web api    https   www microsoft com en-us download details aspx id 34600

User · Answer

This problem started when I did  Remove Unused References   The website still worked on my local machine  but did not worked on the server after publishing     I fixed this problem by doing the following    Open  Package Manager Console  in Visual Studio Uninstall-Package Microsoft AspNet Mvc Install-Package Microsoft AspNet Mvc

User · Answer

by installing AspNetMVC4Setup exe   Here is the link  https   www microsoft com en-us download details aspx id 30683  solves the issue   by restart reinstalling Microsoft AspNet Mvc Package doesn t help me

User · Answer

I first tried Mohammed Emad s answer - no joy   Then I tried   git clean -x -d -f   which brought me to a new  Roslyn  error which I was able to fix by manually editing my  csproj     Interestingly  after I d read down a bit further down the page on the Roslyn question  I found another suggestion with even more votes  Update-Package Microsoft CodeDom Providers DotNetCompilerPlatform -r    Thinking I d rather implement that than manually edit  csproj  I backed out my  csproj changes  only to find my solution was still working   So after all that  I m wondering if Mohammed s answer  on this page  would have done the trick  had I simply done the git clean first

User · Answer

For similar assembly binding errors   following steps may help    Right click on your Solution and click Manage Nuget Packages for Solution     go to Consolidate Tab  last tab  and check if any any differences between packages installed in different projects inside your solution  specially pay attention to your referenced projects which may have lower versions because they usually are less noticed  consolidate specially packages related to your assembly error and note that many packages are dependent on some other packages like   code  amp    api  amp      after resolving all suspected consolidations   rebuild and rerun the app and see if the assembly bindings are resolved

User · Answer

I uninstalled ASP NET MVC 4 using the Windows Control Panel  then reinstalled it by running AspNetMVC4Setup exe  which I got from https   www microsoft com en-us download details aspx id 30683   and that fixed the issue for me   In other words  I didn t need to use Nuget or Visual Studio

User · Answer

I was getting the same error when i upgrade MVC4 to MVC5 version  Firstly i Upgraded the calling assembly which was depends on    gt  System Web WebPages Razor  Version 2 0 0 0   after that updated the web config files under the Views folder   updated following packages from   lt configSections gt       lt sectionGroup name  system web webPages razor  type  System Web WebPages Razor Configuration RazorWebSectionGroup  System Web WebPages Razor  Version 2 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35  gt         lt section name  host  type  System Web WebPages Razor Configuration HostSection  System Web WebPages Razor  Version 2 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35  requirePermission  false    gt         lt section name  pages  type  System Web WebPages Razor Configuration RazorPagesSection  System Web WebPages Razor  Version 2 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35  requirePermission  false    gt       lt  sectionGroup gt   lt  configSections gt    to    lt configSections gt       lt sectionGroup name  system web webPages razor  type  System Web WebPages Razor Configuration RazorWebSectionGroup  System Web WebPages Razor  Version 2 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35  gt         lt section name  host  type  System Web WebPages Razor Configuration HostSection  System Web WebPages Razor  Version 3 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35  requirePermission  false    gt         lt section name  pages  type  System Web WebPages Razor Configuration RazorPagesSection  System Web WebPages Razor  Version 3 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35  requirePermission  false    gt       lt  sectionGroup gt    lt  configSections gt    and also updated   lt host factoryType  System Web Mvc MvcWebRazorHostFactory  System Web Mvc  Version 4 0 0 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt    to    lt host factoryType  System Web Mvc MvcWebRazorHostFactory  System Web Mvc  Version 5 2 7 0  Culture neutral  PublicKeyToken 31BF3856AD364E35    gt    these steps works for me

User · Answer

I also received this error and tried everything I could find online and it wouldn t go away  In the end  I just downgraded MVC from 5 2 3 to 4 0 40804  I don t like this solution because eventually I ll need to use MVC 5  but it works for now  Hope this helps others

User · Answer

If earlier working project crashing suddenly with mentioned error you can try following solution    Delete the bin folder of respective web service project  Build   This worked for me

User · Answer

After my PC got completely reinstalled  I got the error described here  VS 2017 was reinstalled but  ASP NET Web Pages 2  was not reinstalled  After reinstalling  ASP NET Web Pages 2   the problem was solved   See also  Could not load file or assembly System Web WebPages Razor    Version 3 0 0 0 or one of its dependencies

User · Answer

So simple  In Nuget Package Manager Console   Update-Package Microsoft AspNet Mvc -Reinstall

User · Answer

I downgraded via NuGet to MVC 4 and then upgraded again to 5 2 7 and it fixed this issue

User · Answer

Short  In you have this problem with a pure Web API project  and thus don t need razor   try to add it anyway  rebuild  then remove it   Long story  I had this problem with a brand-new pure Web API project  except that the stacktrace pointed  System Web Mvc  as Calling assembly  see Darin s answer   No reference to MVC  Razor or anything like that in my project though    I decided to add the MVC packages  AspNet Mvc  AspNet WebPages and AspNet Razor  to check if there was any subsequent problem  The WebApi app then launched perfectly fine  Then I removed the exact same packages and everything was still OK  Hope it helps someone

User · Answer

In ASP NET MVC 4  the namespace is not System Web WebPages Razor  but System Web Razor  That worked for me  change your web config

User · Answer

how do I find out what is referencing System Web WebPages Razor v2 0 0 0    Just read your exception stacktrace   Calling assembly   Microsoft Web Helpers  Version 2 0 0 0  Culture neutral  PublicKeyToken 31bf3856ad364e35   So it seems that you are using the Microsoft Web Helpers which in turn depends on System Web WebPages Razor  Version 2 0 0 0

User · Answer

After much pain  googling and hair pulling  I ended up uninstalling MVC 4 using nuget  deleting all references to MVC  razor and infrastructure from the web config  deleting the dlls from the bin folder - then using nuget to reinstall everything  It took less time then trying to figure out why the dlls did not match

User · Answer

I was getting the same error after adding an unnecessary reference to System Web Mvc   I removed all the references I could find  but nothing seemed to work   I finally deleted the project s bin folder and the error went away after a rebuild

[asp.net-mvc-3] Could not load file or assembly 'System.Web.WebPages.Razor, Version=2.0.0.0

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