I'm not sure whether this is an issue with Umbraco or the Cassette.aspnet package, but as I've found a workaround I thought I'd post it on here in case the info helps anyone out.

It would be nice to hear from anyone who can tell me what the actual issue might be though, as I came upon the solution pretty much by accident.

Environment:

1. I'm using Umbraco V6

2. I'm using Visual Studio Premium 2012

3. I'm using IIS Express

4. I'm using Nuget to install packages

Issue:

When I install the the Cassette.aspnet (asset managment) package via Nuget, I see only blank browser screens whenever I run my project, although the Umbraco back office still seems fine.

Solution:

In web.config, I moved the following line (in the system.webServer / modules section) to the very top of the modules section; so that it's above all other module registrations:

<add name="CassetteHttpModule" type="Cassette.Aspnet.CassetteHttpModule, Cassette.Aspnet" />

And hurrah, everything works fine again :)

As I mentioned, it would be nice if anyone can shed some light on what the issue might be, but hopefully my solution can at least provide some help for someone expreiencing the same issue.