Here’s an interesting Windows gotcha that affects both Windows 10 and 11. There’s an interval setting value in these OSes that controls how long Windows.old stays on your system disk before it gets deleted. It’s called the “OS uninstall window” and it’s set to 10 days by default, though any value from 2 through 60 (days) is legal. That said, you can only see and manipulate this value if Windows.old is present on the target system. That’s what the title means when it says “Windows.old required for uninstall window access.”

Why Is Windows.old Required For Uninstall Window Access?

God only knows (and possibly a few Microsoft OS engineers). That’s just the way it works. Indeed the relevant MS Learn article doesn’t comment on the why; it only documents the how. I had to go to Google to get an explanation for what you see in the lead-in graphic — namely, that when you run the DISM command that tells you the current uninstall window value for Windows.old, it throws an error if there’s no Windows.old present on your system for it to inspect. Weird.

The best explanation I found is at SuperUser.com. The short answer to “Why an error and not a number?” reads simply “No, you are too late.” That is, once Windows.old is removed, the command no longer works the way one might presume it should. In short, if no Windows.old is present, the OSUninstallWindow value is not available, nor can it be reset. Again: Weird.

Even weirder: you’d think there would be a registry value to control this. But alas, as Copilot informs me and my truth-check research confirms “There isn’t a specific registry value in Windows 10 or 11 that directly controls the OSUninstallWindow value.” It’s just another Windows oddity for the ages. Now I know (and now, you do, too). Cheers!