I was getting the below error while building a Plugin Project. I was really shocked and checked the references which has Micrsoft.XRM.SDK.dll 7.0 version referenced.
Reason for it is CRM 2015 SDK was built on .Net 4.5.2 Framework and the Visual studio does not support 4.5.2.
- Just download .Net Framework 4.5.2 from here
- Goto Project Properties and change the framework.
Hope this helps.