Trados Studio 2015 Freelance to 2017 Freelance upgrade issue

I have purchased the upgrade to Trados Studio 2017 but I can't do the upgrade from Trados Studio 2015. I did not deactivate the license for 2015. When I want to install the 2017 version the error message says: "Setup did not compleete: Package SDL WorldServer Components could not be installed. Another installation is already in progress. Complete that installation before proceeding with the install. Error number 1618."