I'm trying to figure out the original operating system installed on some of my Windows Servers. Currently, they're running Windows Server 2019, and I know they were upgraded from 2016, but I don't know if 2016 was a fresh install or if those servers were originally running 2012 R2 before the upgrades. Is there a way to trace back and find out what the original OS was?
5 Answers
You can check the registry at `ComputerHKEY_LOCAL_MACHINESYSTEMSetupUpgrade`. If that key exists, it means the system was upgraded. Look for `DownlevelBuildNumber`—that tells you what version was originally installed. There might be additional details under `Source OS (Updated on xxx)` which will clarify further upgrades.
Lastly, consider running `systeminfo | find "Original"` in the command prompt; it can show the install date. Just be aware that it might give different results depending on your specific version.
You might want to check user profiles and application folders as those usually remain intact after an inplace upgrade. Also, examining folder creation dates in Program Files could provide some clues.
Another place to look is the setupact.log file located at C:WindowsPanther. That log typically contains information on how the machine was originally set up, especially if it was automated. Just a heads-up, those logs can be massive since they keep a detailed history of installations and upgrades.
If you have the original purchase quotes, that could be a goldmine. For instance, if it was a DELL machine, entering the service tag on their support site usually reveals the original OS it shipped with.
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