SSRS Issue - Request length exceeds a certain amount

Error description: Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server. The status code returned from the server was: 500

Solution: This problem is being caused by SQL server stopping a report being run because the request length exceeds a certain amount.

Locate the web.config files for the ReportManager & ReportServer in WCALQK8B server, these should be found somewhere like this:

C:\Program Files\Microsoft SQL Server\MSRS11.MSSQLSERVER\Reporting Services\ReportManager\Web.config

C:\Program Files\Microsoft SQL Server\MSRS11.MSSQLSERVER\Reporting Services\ReportServer\Web.config

Once located you need to edit the web.config files for both and add the following bit of code:

<appSettings>

<add key="aspnet:IgnoreFormActionAttribute" value="true" />

<add key="aspnet:MaxHttpCollectionKeys" value="100000" />

</appSettings>

These app settings should be added between between /system.web and runtime nodes, so it should look something like the following:

</system.web>

<appSettings>

<add key="aspnet:IgnoreFormActionAttribute" value="true" />

<add key="aspnet:MaxHttpCollectionKeys" value="100000" />

</appSettings>

<runtime> 

NOTE: The ReportManager may already have an app settings node so you will only need to paste the two add key lines.The ReportServer will more than likely require all 4 lines (including the open and close appsettings nodes.

Save these web.config files and restart the reporting service.