I’m trying to find out where Windows stores information about updates that have been hidden. There is another question that asks this, but the location was not actually given, only a method for modifying the hidden updates without going through the official WU interface.

The reason I want to know is because Windows Updates creates 1.3GB of files in %systemroot%\SoftwareDistribution\DataStore and %systemroot%\Logs\CBS which I delete after doing updates. The problem is that last time I used WU, all of the previously hidden updates were restored, leading me to suspect that WU probably stores the hidden flags in the absurdly massive (and bloated and almost completely empty) DataStore.edb file—storing them in the various log files doesn’t seem feasible.

Normally, I would simply do some tests to confirm, but considering that WU takes almost two hours every time it runs, I am quite averse to doing that.

Does anybody know where Windows stores hidden-update settings?

  • 1
    Is this related to a particular version of Windows? – CharlieRB Feb 19 '16 at 15:49
  • @CharlieRB, In my case Windows 7, but as far as I have seen, WU has used the same mechanism for a while. – Synetech Feb 19 '16 at 16:02
  • 2
    you already posted the answer: DataStore.edb – magicandre1981 Feb 19 '16 at 16:44
  • Yes, but it was just a guess. Now it is a fact. Yay science! – Synetech Feb 19 '16 at 19:22

I was hoping to spend Friday getting some work done, but I went ahead wasted it doing the test (while watching some educational videos). Now I—and everyone else—have concrete, tested confirmation rather than just a suspicion. In order to reduce interactions and confounding variables, I started with the least likely candidates.


First to go was CBS.log (the file involved in SFC). Perhaps not surprisingly, the hidden updates were still listed.

Next was the SoftwareDistribution\DataStore\Logs directory. These log files are actually not empty and filled with text, but still compress to next to nothing (probably due to the fact that they are Unicode). Hidden updates preserved.

Finally, DataStore.edb got the axe. Sadly, this caused the hidden updates to reset.

I was really hoping this was not the case, but unfortunately it is. Where in the file the updates are flagged hidden is anyone’s guess. I found a bit of information on the Extensible Storage Engine format, but it’s not really worth the effort because keeping the file does not seem to make WU scans go any faster. I have tried that, and it still took a very long time. (I may have exaggerated with two hours, but still, a good 45-60 minutes regardless of the presence of DataStore.edb.)



As a work-around (I am really getting tired of having to work around every problem in every program), I suggest that anyone who is in this situation could simply compress the file and then delete it. Since the file is almost completely empty, it compress >1GB down to just ~17MB. Then you can decompress it when performing an update check, the re-compress it after. The compression is surprisingly fast even with maximum settings. This has a few problems though:

  1. It still adds wear and tear on the drive.
  2. It requires enough space to decompress before performing updates.
  3. This work-around only applies to those who do manual updates, therefore anyone anyone who uses automatic updates (or using Windows 10) will have to bite the bullet and waste a lot of space (though you can still delete the 150MB CBS.log file without affecting the hidden update list).

External List

Another option is to make a list of the updates you have hidden to make it slightly easier to deal with. Unfortunately the WU interface does not provide a way to copy the list to the clipboard, and as of Vista, Microsoft switched Explorer to a different set of controls, so you cannot extract the list with something like SysExporter. Therefore, you will have to either take a screenshot of the hidden-update list, or manually write them all down.

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