If you have nested ASP.Net applications, any HttpModules defined in the web.config of parent apps propogate down to the children. This can be desirable in some situations, but totally unwanted in others.

The easy way to eliminate the impact of parent HttpModules is to add a element in the child app's web.config. Sounds simple enough, until you try it.

Turns out that because of the way ASP.Net processes the web.config, even if you are clearing out HttpModules in a child app's web.config, you still need to have the requisite assemblies for the HttpModules in the child app's bin folder. Otherwise the child app will not run.