Could not load file or assembly 'Microsoft.CodeDom.Providers.DotNetCompilerPlatform

Question

Other articles on here haven't been able to solve my issue. The following errors are being thrown when I run my ASP.NET MVC5 Web Project.

Anyone got an idea where I am going wrong?

Could not load file or assembly 'Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.8.0, 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)    === Pre-bind state information === LOG: DisplayName = Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.8.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35  (Fully-specified) LOG: Appbase = file:///C:/Users/Teije/Documents/git/Project2.2/HaarlemFestival-Web/  LOG: Initial PrivatePath =         C:\Users\Teije\Documents\git\Project2.2\HaarlemFestival-Web\bin Calling assembly : (Unknown) === LOG: This bind starts in default load context. LOG: Using application configuration file: C:\Users\Teije\Documents\git\Project2.2\HaarlemFestival-Web\web.config LOG: Using host configuration file: C:\Users\Teije\Documents\IISExpress\config\aspnet.config LOG: Using machine configuration file from C:\Windows\Microsoft.NET\Framework\v4.0.30319\config\machine.config. LOG: Post-policy reference:     Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.8.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35 LOG: Attempting download of new URL file:///C:/Users/Teije/AppData/Local/Temp/Temporary ASP.NET Files/vs/b2d7334d/e3876cf7/Microsoft.CodeDom.Providers.DotNetCompilerPlatform.DLL. LOG: Attempting download of new URL file:///C:/Users/Teije/AppData/Local/Temp/Temporary ASP.NET     Files/vs/b2d7334d/e3876cf7/Microsoft.CodeDom.Providers.DotNetCompilerPlatform/Microsoft.CodeDom.Providers.DotNetCompilerPlatform.DLL. LOG: Attempting download of new URL file:///C:/Users/Teije/Documents/git/Project2.2/HaarlemFestival-    Web/bin/Microsoft.CodeDom.Providers.DotNetCompilerPlatform.DLL. WRN: Comparing the assembly name resulted in the mismatch: Build Number ERR: Failed to complete setup of assembly (hr = 0x80131040). Probing terminated. 

Answer 1

We just had this error in one of our test environments. The problem was in the web.config file. The section had settings to reference the DotNetCompilerPlatform assembly, but had the wrong version number. We updated web.config to the proper version number and it fixed the error.

<compilers>   <compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:default /nowarn:1659;1699;1701" />   <compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.5.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:default /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer+" /> </compilers> 

Answer 2

This problem comes from your Nuget package Microsoft.CodeDom.Providers.DotNetCompilerPlatform.

It is the wrong version. You can remove the Current Version then install again from Nuget.