I've rewrote a dated installscript installer as an MSI project. (I'm fairly experienced with MSI projects but not at all with Installscript)
New install works fine as an MSI - it works better than it used to and therefore the rewrite has been generally justified, although I have one outstanding issue...
I need to ensure that any previous version of the product is uninstalled. It doesn't matter whether this is automatic or whether it forces the user to do so, before allowing the new install. I've looked at the old installscript project and I can't find any record of an upgrade code, so I guess this was introduced for MSIs.
I tried setting the product code to be the same, hoping it may detect that a previous version is installed, and force the user to uninstall before continuing. However, the new product sort of just installs in addition to the old one, leaving components from both installs present. The add/remove programs dialog shows only one entry for the product, presumably due to the GUID clash.
Any ideas on where to go next would be greatly appreciated.
Although I can test for a previous version using an install condition and force the user to uninstall the old version, it would be better if the old version could be uninstalled automatically, so that deployment using group policies is immediately possible.
I've a feeling that this isn't going to be possible...
Windows Installer is only designed to upgrade and maintain Windows Installer based products. There's no built-in functionality to upgrade or manage installers that don't use MSI.
You're probably going to want to roll a custom action for this situation. You could probably just locate instances of the previous product codes on the machine and remove them procedurally in a Custom Action of some kind.
