Whenever I build an installer with a new version number, when the user tries to install the new one it stops and says user must UNinstall the current version. How do I make it automatically overwrite the current version?
We also came across this. The reason is that the Product Code is the same between your builds (even you change the version number). Remember that the Upgrade Code must always be the same!
I'm sure that, if you change the Product Code it will upgrade correctly. If you release a new version it is always a good idea to change the Product Code, but for intermediate builds this could be a little cumbersome.
Therefore, play with the Upgrade Path. And set the Upgrade Path to include the version you are installing. This worked for us when creating new ISX projects, we however had problems with older upgrades projects.
Alternatively you can make an automated build tool that changes the version number and product code before building the project. As hint, you can use the "WindowsInstaller.Installer" object and treat the ISX project file as a database looking for e.g. the "ProductCode" property.
