From here: http://www.isolutionspartners.com/sql-reporting-services-error-maximum-request-length-exceeded/
You could, quite honestly, run into this error in a lot of situations involving a web app, but we’re talking specifically about SSRS in this post. The basic problem here, is that your posting an amount of data to a web app larger than it is configured to accept. Hence, it is throwing an error.
It’s an easy fix though. You’ve got to adjust the web.config for the web app, which in the case of reporting server, is usually somewhere like this:
For SQL Server 2012: C:\Program Files\Microsoft SQL Server\MSRS11.MSSQLSERVER2012\Reporting Services\ReportServer
Find the web.config file for your reporting services instance, open it up, and track down the line that looks something like this
executionTimeout = "9000" />
Now just add a max request length attribute in there to fix the problem, adjust your size as needed. This is 5meg.
executionTimeout = "9000" maxRequestLength="500000" />
And now you’ll need to restart IIS. start->run->”iisreset”
On the design surface, click the row or column handle of the tablix data region to select it. The Grouping pane displays the row and column groups.
On the right side of the Grouping pane, click the down arrow, and then click Advanced Mode. The Row Groups pane displays the hierarchical static and dynamic members for the row groups hierarchy and the Column groups pane shows a similar display for the column groups hierarchy.
Click the static member that corresponds to the static member (row or column) that you want to remain visible while scrolling. The Properties pane displays the Tablix Member properties.
If you don’t see the Properties pane, click the View tab at the top of the Report Builder window and then click Properties.
In the Properties pane, set RepeatOnNewPage to True.
Set KeepWithGroup to After.
Repeat this for as many adjacent members as you want to repeat.
Preview the report.
In this scenario, it can be many reasons to cause this problem, even the current user has enough authority to do anything on Report Manager. Please try to do trouble shooting as below:
- Run the browser as an Administrator.
- Add the Report Manager URL as Compatibility View settings.
- Use http://<servername>/reports instead of using Localhost.
- If the steps above still can't make you see the dropdown menu, it might caused by corrupt reportingservices.js file. Please try to restore this file on server.
Reporting Services provides some nice options to allow user’s to feel like they are interacting with the data, by expanding lower levels of detail when they click on the plus (+) sign in the report’s tablix. You can also set the initial Toggle state of report items as expanded i.e. (-) sign. There is a catch though in that when you Show your initial state as expanded, the items may expand correctly but the toggle sign appears reversed (i.e. + instead of -).
Nice solution to the problem demonstrated Here.