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GAC_MSIL version reference conflict error on MSBuild compilation


Hi All,

I am getting below error when compiling ASP.NET website project using MSBuild v16.0 (32bit) on public agent.

Note: It works fine on local machine using VS2019 and also working fine on public agents with MSbuild 14.0

Here is the error:

The type 'System.Web.Helpers.AntiForgery' exists in both 'c:\Windows\Microsoft.NET\assembly\GAC_MSIL\System.Web.WebPages\v4.0_2.0.0.0__31bf3856ad364e35\System.Web.WebPages.dll' and 'c:\Windows\Microsoft.NET\assembly\GAC_MSIL\System.Web.WebPages\v4.0_1.0.0.0__31bf3856ad364e35\System.Web.WebPages.dll'

Here is the web.config file:

<compilation debug="true" targetFramework="4.8" batch="false">
<add assembly="stdole, Version=7.0.3300.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A"/>
<add assembly="Office, Version=, Culture=neutral, PublicKeyToken=71E9BCE111E9429C"/>
<add assembly="System.Web.Helpers, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>
<add assembly="System.Web.WebPages, Version=, Culture=neutral, PublicKeyToken=31BF3856AD364E35"/>

Solutions i tried:

1. Added batch=false in the compilation element.

2. Tried deleting one of the System.Web.WebPages.dll from the system. But the dll is autogenerated back on the system and set batch=true in the compilation element.

3. Have requested to delete the ASP.NET temp folder and IIS reset. (In-progress)


Kindly help me out to solve the above issue.

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