Error received after upgrade to 12.9 C3 or C4.
The ReadMe file for these Cumulative patch state the following:
Add below line under ‘httpModules’ section.
<add name="QueryStringModule" type="CA.Common.Web.HttpModules.QueryStringModule"/>
Wrong content for this function
Do not add this entry; or remove it from the Web Server folder web.config file.
If changed please run an iisreset