Solution: Carefully comb through the project and filter out all references. Remove the unwanted references and replace the ones remaining with the version you want. Ex. I had 184.108.40.20600-0 and 220.127.116.1100-0. I wanted the newer one as it came with .Net 3.5 which I was using to build the project. So I replaced all the 18.104.22.16800-0 with 22.214.171.12400-0. And the error was gone!!!