IIS 7.5 – Parser Error Message: Could not load file or assembly Microsoft.ReportViewer.WebForms

When deploying a new application to IIS 7.5 on Windows Server 2008 R2 (test server). I got the following error:
Server Error in '/' Application.
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Configuration Error


Description: An error occurred during the processing of a configuration file required to service this request. Please review the specific error details below and modify your configuration file appropriately.


Parser Error Message: Could not load file or assembly 'Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' or one of its dependencies. The system cannot find the file specified.


Source Error:


Line 24: <add assembly="System.Web.Extensions.Design, Version=4.0.0.0, Culture=neutral, PublicKeyToken=31BF3856AD364E35" />
Line 25: <add assembly="System.Windows.Forms, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B77A5C561934E089" />
Line 26: <add assembly="Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
Line 27: <add assembly="Microsoft.ReportViewer.Common, Version=10.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />
Line 28: <add assembly="Microsoft.Build.Framework, Version=4.0.0.0, Culture=neutral, PublicKeyToken=B03F5F7F11D50A3A" />


Source File: C:\inetpub\wwwroot\web.config Line: 26


Assembly Load Trace: The following information can be helpful to determine why the assembly 'Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a' could not be loaded.


WRN: Assembly binding logging is turned OFF.
To enable assembly bind failure logging, set the registry value [HKLM\Software\Microsoft\Fusion!EnableLog] (DWORD) to 1.
Note: There is some performance penalty associated with assembly bind failure logging.
To turn this feature off, remove the registry value [HKLM\Software\Microsoft\Fusion!EnableLog].


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Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1

Parser Error Message: Could not load file or assembly 'Microsoft.ReportViewer.WebForms...

I forgot to install Microsoft ReportViewer 2010 Redistributable.

It also can be installed from the following location:
C:\Program Files\Microsoft SDKs\Windows\v7.0A\Bootstrapper\Packages\ReportViewer\ReportViewer.exe

Microsoft Report Viewer 2010 Redistributable Package Setup is easy 3 step process:

Microsoft Report Viewer 2010 Redistributable Package Setup
Microsoft Report Viewer 2010 Redistributable Package Setup 2
Microsoft Report Viewer 2010 Redistributable Package Setup Finished

11 thoughts on “IIS 7.5 – Parser Error Message: Could not load file or assembly Microsoft.ReportViewer.WebForms”

  1. You also add the reference Microsoft.ReportViewer.WebForms then set properties ‘copy to local’ to true.

  2. We have the Report Viewer Redistributable installed and still getting this same error.

    Can anyone help with what else i can check?

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