Dynamic Operations Can Only Be Performed In Homogenous AppDomain for Sharepoint sites

This issue occurs when you are using any dynamic operation on any page or web part or any other form in your code. Then this problem occurs.

"legacyCasModel" forces a non-homogeneous domain as it is the pre-.net4 way of doing things. This means that dynamic objects and your older CAS library are incompatible.

To solve this issue just go to your web.config file and search for <trust legacyCasModel="true" level="Full" />


Here you need to set false for legacyCasModel. Save the config file. This will solve this problem

<trust legacyCasModel="false" level="Full" />