Do you have a sneaking suspicion that your Windows PC is losing disk space? If so, it may not be your imagination, at least not if your system has been hit by a known bug that makes a single file balloon to absurd proportions.

A particular file in Windows 11 can grow to the point that the loss in disk space becomes noticeable. The culprit is a system file named CapabilityAccessManager.db-wal, as spotted and described by Windows Latest. Part of the Capability Access Manager Service, this otherwise obscure file manages permissions for apps accessing your camera, microphone, location, and other privacy-minded features. The db-wal extension indicates it stores changes in a write-ahead log before they're written to the main database.

The file itself can certainly grow as it needs to keep track of more data. However, it should top out at no more than a megabyte or two. Instead, the bug in Windows seems to cause it to expand to as much as 500GB, according to one Redditor who posted a message a year ago (yep, it's been around at least that long).

How can you tell if you're affected? One way is to check the size of your Windows system files. Go to Settings, select System, and then click Storage. Under the first bar image, click the link for "Show more categories." If the category for System & reserved shows no more than two or three dozen gigabytes, you're in the clear. But if it indicates a size stretching beyond 100GB, your system is likely affected.

I checked all my Windows 11 environments, including those directly on PCs and those in virtual machines. On all except one, the size ranged from 5GB to 25GB. But on my primary Windows 11 laptop, the size hit 151GB.

Okay, but how do you know that CapabilityAccessManager.db-wal is to blame? The file itself is housed at C:\ProgramData\Microsoft\Windows\CapabilityAccessManager. However, Windows denies you access to that folder by default, and changing permissions on a system folder is not recommended. Instead, Windows Latest recommends running a utility like WizTree, TreeSize, or WinDirStat in admin mode. But there's an easier option using the built-in Robocopy tool. Open a command prompt as an administrator and type: robocopy "C:\ProgramData\Microsoft\Windows\CapabilityAccessManager" "%TEMP%\CAMCheck" /L /B /R:0 /W:0 /BYTES /NP.

I ran that Robocopy command on my own Windows 11 installations. Almost all reported a size of around 57,000 bytes, or a fraction of a megabyte. But on my primary Windows 11 laptop, CapabilityAccessManager.db-wal weighed in at 7GB - not out of control but still much larger than normal.

Though the bug has been around for at least a year, Microsoft has finally gotten around to fixing it. In the June 23 optional preview update, a note says: "This update improves disk space usage for the CapabilityAccessManager.db-wal file." That likely explains the difference among my PCs. I've already run this preview update in my Windows 11 virtual machines, but not on my laptop.

If you want to install this one, head to Settings and select Windows Update. You should see that the 2026-06 Preview Update is available. Just click Download & Install to grab it. But keep in mind that these preview updates are optional for a reason - they're designed more for IT admins and power users who want to test them ahead of the general release.

The same updates are packaged into the following month's official Patch Tuesday rollout, which is designed for all Windows users. If you can live with the shot to your disk space, I'd advise waiting until July 14 to grab the entire mandatory update. At that point, this file size bug should be squashed for everyone.