Could not load file or assembly 'Microsoft.ReportViewer.WebForms'

Question

I am trying to use the report viewer in asp.net and have uploaded my site. However, when my page containing the report viewer is loaded, it shows the following error:

<

Answer 1

I ran into the same error. My web app was pointed towards report viewer version 10.0 however if 11.0 is installed it adds a redirect in the 10.0 .dll to 11.0. This became an issue when 11.0 was uninstalled as this does not correct the redirect in the 10.0 .dll. The fix in my case was to simply uninstall and reinstall 10.0.

Answer 2

I had this error with an old webforms app. Turns out there was a line in the markup causing the issue. I removed it and the error disappeared.

<%@ Register assembly="Microsoft.ReportViewer.WebForms, Version=10.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a" namespace="Microsoft.Reporting.WebForms" tagprefix="rsweb" %>

Answer 3

Upload the file Microsoft.ReportViewer.WebForms.dll to your bin directory of your web applicaion.

You can find this dll file in the bin directory of your local web application.

Answer 4

I've solved the problem by copying both

• Microsoft.ReportViewer.WebForms.dll from C:\Program Files (x86)\Microsoft Visual Studio 12.0\ReportViewer
• and Microsoft.reportviewer.common.dll from C:\Program Files\Microsoft Office\Office15\ADDINS\PowerPivot Excel Add-in

into bin folder (website).

Of course web.config must have:

    <httpHandlers>
        <add path="Reserved.ReportViewerWebControl.axd" verb="*" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" validate="false" />
    </httpHandlers>

    <assemblies>

        <add assembly="Microsoft.ReportViewer.WebForms, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845DCD8080CC91" />
        <add assembly="Microsoft.ReportViewer.Common, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845DCD8080CC91" />
    </assemblies>

    <buildProviders>
        <add extension=".rdlc" type="Microsoft.Reporting.RdlBuildProvider, Microsoft.ReportViewer.WebForms, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
    </buildProviders>

    <system.webServer>
        <validation validateIntegratedModeConfiguration="false" />
        <handlers>
            <add name="ReportViewerWebControlHandler" preCondition="integratedMode" verb="*" path="Reserved.ReportViewerWebControl.axd" type="Microsoft.Reporting.WebForms.HttpHandler, Microsoft.ReportViewer.WebForms, Version=11.0.0.0, Culture=neutral, PublicKeyToken=89845dcd8080cc91" />
        </handlers>
    </system.webServer>

And that's all. For me is ok.

Hope this helps.

Answer 5

I had the same error for a different package. My problem was that a dependent project was referencing a different version. I changed them to be the same version and all was good.

Answer 6

This link gave me a clue that I didn't install a required update (my problemed concerned version nr, v11.0.0.0)

ReportViewer 2012 Update 'Gotcha' to be aware of

I installed the update SQLServer2008R2SP2

I downloaded ReportViewer.msi, which required to have installed Microsoft® System CLR Types for Microsoft® SQL Server® 2012 (look halfway down the page for installer)

In the GAC was now available WebForms v11.0.0.0 (C:\Windows\assembly\Microsoft.ReportViewer.WebForms v11.0.0.0 as well as Microsoft.ReportViewer.Common v11.0.0.0)