I am using InstallShield 2020 R3 and Visual Studio 2017 and i am seeing this error. 1) Initially I updated my *.isproj to change the ToolsVersion from 3.5 to 4.0 but this does not seem to work.  Also I don't know why it keeps going back to 3.5. 2) After the error occur , I have to go to Visual Studio->open the project->Application->Output type and change the value either Class Library or Windows Application (depending on where it was set) and then rebuild then error is gone, any idea why? ... View more