I have an InstallShield InstallScript MSI project that contains the FLEXnet Connect without Software Manager merge module. The version of this product is 6.0.32. I created a second installer for version 6.1 that also contains the FLEXnet Connect without Software Manager merge module. When I perform a major upgrade on a system that contains the 6.0.32 version I get a message in the MSI log stating:
Disallowing installation of component: {FF970098-B748-427B-B946-AA8E1A1F82AD} since the same component with higher versioned keyfile exists
The component is referencing the isusweb.dll file located in the FLEXnet Connect folder.
It looks like this check occurs prior to the 6.0.32 product being removed. The install proceeds to remove the 6.0.32 product, which removes isusweb.dll. During the 6.1 install the isusweb.dll is not put back because of the component version check.
The upgrade succeeds. When I attempt to run the application from a shortcut it verifies the components. Since the isusweb.dll is missing the MSI attempts a repair, then cannot find the MSI and does not allow the application to open.
Is there some way to get the merge module to always overwrite?
This sounds suspiciously like this bug:
http://support.microsoft.com/kb/905238/en-us
and I've come across this bug and you do see that log message, and RemoveExistingProducts is early in the install. It decides to not install the file based on the higher version being there, but doesn't re-evaluate that decision after the REP removes it. Then a repair restores it when you use a shortcut. The bug should apply only to files in the GAC or SxS, so that's a bit puzzling.
If you can schedule REP at the end of the transaction sequence (InstallExecute, REP, InstallFinalize) that should fix it - might be worth a try, all other effects of the move being ok.