I just updated to VS2015 after receiving a new laptop. I opened a project that was built in VS2013.
Hit 'build' and received the same error as Roberto did 5 years ago.
To be clear, the project successfully built yesterday when I had VS2013. I did not change any references myself, altho a new 'lib' folder was created in the solution with the current Telerik dll files.
I will be submitting a ticket, but wanted to raise visibility of this to the community at large.