Product:
Cognos Analytics 11.0.7
Microsoft Windows 2012 R2

Problem:
When you inside Cognos Administration on Dynamic Cubes click on “properties” for a specific cube you get a error.
If you surf direct to the dispatcher on port 9300, and do the same thing inside Cognos Connection you do not get a error. Therefor the error is with IIS. Check the windows event log for more details:

Error message:
An unhandled exception has occurred.
/ibmcognos
C:\Program Files\ibm\cognos\analytics\webcontent\
w3wp.exe
IIS APPPOOL\ICAPool
HttpException
The length of the query string for this request exceeds the configured maxQueryStringLength value. at System.Web.HttpRequest.ValidateInputIfRequiredByConfig() at System.Web.HttpApplication.PipelineStepManager.ValidateHelper(HttpContext context)

Solution:
Withing IIS Default Web Site > ibmcognos > bi

Click on ‘Configuration Editor’

Select Section ‘system.web/httpRuntime’
set the following attribute setting –

maxQueryStringLength = 2048 -> 8192
maxRequestLength = 4096 -> 8192

Restart IIS

More information:
https://www.ibm.com/support/knowledgecenter/en/SSEP7J_11.0.0/com.ibm.swg.ba.cognos.inst_cr_winux.doc/t_gateway_iis.html

Adjust request size limits. (Sometimes this settings does not work and you need to edit as above).
Select the bi directory under the ibmcognos application created earlier.
Double-click Request Filtering.
Click Edit Feature Settings… from the right-hand panel.
Set Maximum URL length (bytes) to 8192.
Set Maximum query string (bytes) to 8192.
Click OK.