How to find the UpgradeCode and ProductCode of an installed application in Windows 7

Question

I have an application installed on my machine. I also have its source code but somehow the ProductCode and UpgradeCode of this application were changed.

Now I want t

Answer 1

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IMPORTANT: It's been a while since this answer was originally posted, and smart people came up with wiser answers. Check How can I find the Upgrade Code for an installed MSI file? from @ Stein Åsmul if you need a solid and comprehensive approach.

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Here's another way (you don't need any tools):

• open system registry and search for HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Uninstall key (if it's a 32-bit installer on a 64-bit machine, it might be under HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Microsoft\Windows\CurrentVersion\Uninstall instead).
• the GUIDs listed under that key are the products installed on this machine
• find the one you're talking about - just step one by one until you see its name on the right pane

This GUID you stopped on is the ProductCode.

Now, if you're sure that reinstallation of this application will go fine, you can run the following command line:

msiexec /i {PRODUCT-CODE-GUID-HERE} REINSTALL=ALL REINSTALLMODE=omus /l*v log.txt

This will "repair" your application. Now look at the log file and search for "UpgradeCode". This value is dumped there.

NOTE: you should only do this if you are sure that reinstall flow is implemented correctly and this won't break your installed application.