Can you provide more info about the scenario you are using:
1. When this code is invoked in the Application life cycle?
2. Do you have any custom code on application start, which overrides the default Sitefinity behavior? Maybe in the Global.asax?
3. Do you know about any changes before this error started thrown?
4. Which is the version of Sitefinity?
Finally, you can send us your project, so we could investigate it locally.
the Telerik team
Do you want to have your say in the Sitefinity development roadmap? Do you want to know when a feature you requested is added or when a bug fixed? Explore the Telerik Public Issue Tracking
system and vote to affect the priority of the items