Suppose that you have an installer (not a wix installer) that you downloaded from somewhere. How can you know UpgradeCode of that installer so that you can fill it in in the UpgradeCode section in the new installer that you prepare?
Can I learn it from registry somehow? So the question is basically, how to know the UpgradeCode of a program that is installed in the computer.
Actually my problem is that my product has been installed with another installer and I am now trying to move it to wix installer. However, I can't find upgrade code in previous installer and I want to find it from installed software.
Thanks.
As I posted to WiX users:
I've seen this done by having the upgrade get the uninstall string from the registry, where there should be a command you can use since it's not MSI-based. Whether you should call it in the UI sequence or the execute sequence or both depends on your requirements for silent installs, meaning that you'd need to do it silently in the execute sequence, and perhaps need to alter the uninstall command to make it silent.
The same general idea should work if that install has a standard uninstall shortcut you could get the command from. Either way, you're just using a CA to run an external program, or maybe a Util CAQuietExec kind of thing.
Assuming it's a Windows Installer based installer ( WiX, InstallShield, et al ) you can edit it with ORCA and look at the Property table to see it's UpgradeCode. You may have to first extract it if it was packaged as a self extracting installer.
You can also query the MSI API or look in the registry (HKCR\Installer) for this information. If you go the registry route it's probably easiest to look at the Products/GUID/Sourcelist key and trace it back to a cached MSI and look at it in ORCA. Otherwise you have to learn how to join different datasets and convert Darwin transformed GUIDS back to their original GUID format.
Fire up PowerShell (run as admin) and run this command to get a list of installed products with product code:
Get-WmiObject Win32_Product | Format-Table Name, LocalPackage
You will get a list of all installed MSI products, and a weird looking path to the local cached MSI database. It normally looks something like this:
C:\Windows\Installer\235bbf8.msi
The 235bbf8.msi file name is random, and will be different for each installed product. It is a cached copy of the MSI file that you originally installed. It does not contain cab files (or at least it didn't in older versions of Windows).
You can open that file with the random name from Orca by chosing File -> Open and then pasting in the full path to the file open dialog, and then pressing open. Don't make any changes but check the upgrade code in the Property table. You can also use other MSI tools such as Installshield.
Note that the path C:\Windows\Installer is "super protected" and is not even visible in Windows Explorer before you enable the show hidden folders AND you disable the protect operating system files option. I still believe you can open the file directly if you paste the whole path into Orca - no need to go via Windows Explorer.
来源：https://stackoverflow.com/questions/24326657/wix-how-to-uninstall-previously-installed-application-that-is-installed-using-d