SSRS 2008R2 Parameterized Reports stop working

SSRS 2008R2 Parameterized Reports suddenly stop working

After a recent round of Windows Updates, one of my SQL Server Reporting Server 2008 R2 users complained that reports were not working properly.  After some digging, I realized that in-fact, some of the reports were actually working, it just turned out to be the ones that require parameters.  The error looks like this:


The first thing I noticed was the “Error” message at the bottom that didn’t yield much information:


Although it got me pointed in the direction of something wrong with the Web Server.  In SSRS 2008, Microsoft changed the infrastructure and design of how the reporting services interacts with the different components and also eliminated the need for IIS.  Stacia Misner does a good job explaining this here:

By getting this information it made me realize that there was clearly no reason to continue messing with IIS to try to resolve the issue, so I began searching for the error I found in the log of SQL Server Reporting Services at:

C:\Program Files\Microsoft SQL Server\MSRS10_50.SQLREPORTING\Reporting Services\LogFiles

The error that I found was:

System.Web.HttpException: The URL-encoded form data is not valid. —> System.InvalidOperationException: Operation is not valid due to the current state of the object.

And finally after an extensive search, I found this posting in MSDN:

Looks like there was a Windows Update (KB2656351) that I had installed on Jan 12, 2012 and Possibly another (KB2656356) which did not affect me.  I uninstalled the first KB and rebooted, however, it did not resolve my issue.  By reading through the posting, I attempted the other suggested fix by modifying the web.config file found here:

C:\Program Files\Microsoft SQL Server\MSRS10_50.SQLREPORTING\Reporting Services\ReportManager

Inside the <appSettings> tags:

<add key=”aspnet:MaxHttpCollectionKeys” value=”10000″ />

10000 is just a suggestion, you can set it to the value of your liking depending on the sizes of your parameters.

And my problem was resolved!