I am afraid that the provided information is not sufficient in order to determine what might throw this error. Could you please elaborate a bit more on your scenario:
- Is this a share point project?
- Please stop the Ajax if you use Ajax and let us know how that worked.
- In case of developing a share point project please could you clarify whether you are using the RadScheduler web part?
- Could you please confirm that you are using the latest official release 2014.1.225?
Check out the Telerik Platform - the only platform that combines a rich set of UI tools with powerful cloud services to develop web, hybrid and native mobile apps.