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Repeat Cumulative Updates Need Cleanup

Microsoft pushed out 3 cumulative updates that hit my PCs in September. They appeared on 9/1, 9/13, and 9/26. After the third one came through at month’s end, I found myself thinking: “I wonder if repeat cumulative updates need cleanup.” Dashing into the Disk Cleanup utility (cleanmgr.exe), my presumption appeared warranted. Here’s what I found:

The highlighted item shows 1.64 GB of Windows Updates for cleaning up.

Why Do Repeat Cumulative Updates Need Cleanup?

Each time a Windows client gets something from Windows Update, it receives files in the %windir%\SoftwareDistribution\Download folder. Electing the option shown in the screenshot cleans out that folder, thereby freeing up disk space. It’s also worth noting that, once removed, such updates can no longer be uninstalled. That is, if you click “Uninstall updates” in the Update History window, you won’t see them among the list of items available for removal.

Then too, cumulative updates are a bit different from regular updates. In fact, they “roll up” all updates provided since some checkpoint in time. The three updates that hit my PC in September are best described in Knowledge Base (KB) articles:

KB3194496 (9/29/2016): 402 MB (x86) or 753 MB (x64)
KB3189866 (9/13/2016): 255 MB (x86) or 431 MB (x64)
KB3176938 (9/1/2016): 205 MB (x86) or 331 MB (x64) [Actual release date: 8/31/2016]

Adding those items together for x64 Windows 10 machines, you get 1,515 MB, or 1.48 GB. The Update clean-up number shown in the screenshot is 0.16 GB bigger. Thus, it’s obviously counting other updates from that period as well. But update cleanup removes them all. With usable restore points or image backups prior at hand, one can always roll back their effects. That’s why I don’t worry about cleaning up, either. Given the current cadence of cumulative updates from MS, this is a likely monthly drill for admins.