Hello, If your project has Roslyn references and you are deploying it on an IIS server, you might get unwanted errors on the website as many hosting providers still have not upgraded their servers and hence do not support Roslyn

To resolve this issue, you will need to remove the Roslyn compiler from the project template. Removing Roslyn shouldn't affect your code's functionality. It will work fine.

Try to do the following steps:

1)Remove from following Nuget Packages using command line shown below (or you can use GUI of Nuget Package manager by Right Clicking on Root Project Solution and removing them).

PM> Uninstall-package Microsoft.CodeDom.Providers.DotNetCompilerPlatform PM> Uninstall-package Microsoft.Net.Compilers

2)Remove the following code from your Web.Config file and restart IIS. (Use this method only if step 1 doesn't solve your problem.)

<system.codedom>
<compilers>
<compiler language="c#;cs;csharp" extension=".cs" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.CSharpCodeProvider,
Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4"
compilerOptions="/langversion:6 /nowarn:1659;1699;1701" />
<compiler language="vb;vbs;visualbasic;vbscript" extension=".vb" type="Microsoft.CodeDom.Providers.DotNetCompilerPlatform.VBCodeProvider, Microsoft.CodeDom.Providers.DotNetCompilerPlatform, Version=1.0.0.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35" warningLevel="4" compilerOptions="/langversion:14 /nowarn:41008 /define:_MYTYPE=\&quot;Web\&quot; /optionInfer+" />
</compilers>

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