Windows 11 C Drive Full? Check This Hidden File
If the C drive on your Windows 11 PC keeps filling up and you cannot find what is using the space, a known bug may be the reason. It involves one file, CapabilityAccessManager.db-wal, which sits in a locked system folder. On affected PCs it can grow from a few megabytes to tens or even hundreds of gigabytes.
Microsoft has fixed it with a Windows update. The catch is that Windows gives you no easy way to see the file, and much of the advice online for getting rid of it can cause more trouble than the bug. On my own PC the file is only 1.4 MB, and the check below is how I know. It takes a couple of minutes.
KEY TAKEAWAYS
- The file lives in
C:\ProgramData\Microsoft\Windows\CapabilityAccessManager. A healthy one is a few megabytes at most. - Windows will not show you its size. Settings lumps it into System & reserved, and File Explorer reports the folder as 0 bytes. A read-only robocopy command shows the real number.
- The fix is a normal Windows update: KB5095093 in June 2026, carried into the July 2026 security update KB5101650 and the monthly updates after it. Install updates and restart.
- Do not take ownership of the folder or delete the file. People who did reported broken Wi-Fi and screen capture, and in some cases the file grew back anyway.
Prefer to watch? Here is the video, and the steps below link to their moments in it.
Why the Storage page does not show it
Open Settings > System > Storage and click Show more categories. The entry to look at is System & reserved. On my PC it is about 25 GB, which is normal.
That number cannot clear you or convict you. System & reserved also covers things like the page file, the hibernation file and restore points, and Windows does not break it down any further. In one case on Microsoft’s own Q&A forum, the page showed 111 GB when around 40 GB is typical, and nothing on the screen said which file was responsible. To find out, you have to look inside the folder.
Find the hidden folder
The folder is hidden by default, so turn hidden items on first. In File Explorer, choose View > Show > Hidden items.
- Open This PC > Local Disk (C:) > ProgramData.
- Open Microsoft, then Windows.
- Scroll down to CapabilityAccessManager and double-click it.
Windows answers with “You do not currently have permission to access this folder” and a Continue button. Click Cancel. Then right-click the folder, choose Properties, and look at Size. It says 0 bytes, which is not true. Windows simply cannot read inside a folder it has locked, so it reports nothing.
DO NOT CLICK CONTINUE
That button takes ownership of the folder and gives your account permanent access to it. It is the first step in most of the removal guides, and the reasons to avoid it are covered further down.
Watch this step in the video (0:45)
Check the file size with robocopy
There is a way to see inside without unlocking anything. Click Start, type cmd, right-click Command Prompt and choose Run as administrator. Administrator rights are needed because the folder is locked, and this command reads it using backup mode. Then paste this single line and press Enter:
robocopy "C:\ProgramData\Microsoft\Windows\CapabilityAccessManager" "%TEMP%\CAMCheck" /L /B /R:0 /W:0 /BYTES /NPThe /L switch makes robocopy only list files, so nothing is copied, changed or deleted. In the output, find the line ending in CapabilityAccessManager.db-wal. Because of the /BYTES switch, the size is shown in bytes just before the file name.
On my PC it reads 1,421,432 bytes, about 1.4 MB. Divide the number by 1,048,576 to get megabytes, or by 1,073,741,824 for gigabytes. A few megabytes is what a healthy file looks like. If yours is hundreds of megabytes, or gigabytes, you are affected. If the number looks high, run the command again ten minutes later. A file that keeps growing means something is still writing to it.
Watch this step in the video (2:05)
What it looks like when it goes wrong
The file belongs to the Capability Access Manager service, which keeps a record of which apps have asked to use your camera, microphone or location. The .db-wal part is a write-ahead log, a temporary file that a database fills before the changes are merged into the main database. It is meant to be merged and cleared regularly. On affected PCs it keeps growing instead.
A thread on Microsoft’s Q&A forum, CapabilityAccessManager is devouring my hard drive, started in March 2026, shows the damage. The poster’s file had reached 66.5 GB on a 221 GB drive, and the PC was crawling. According to the poster, the Microsoft Support agent had not heard of the problem and, after checking with a supervisor, suggested buying a portable hard drive.
Replies in the same thread describe the file coming back after it was removed, at about 6 GB over two weeks for one person and about 1 GB a day for another. Other people reported 99 GB, 276.5 GB and about 570 GB.
Microsoft has not published a root cause. The first detailed report I could find is a March 2025 thread on the Rainmeter forum, titled “Rainmeter’s WiFiStatus queries cause huge 30GB+ CapabilityAccessManager.db-wal file”. As described in coverage of that thread, a desktop widget was asking Windows about location access around ten times a second, and each request was written to the log. I could not open the thread itself, so treat that detail as reported rather than confirmed. Other people in the Q&A thread blamed Dell SmartByte and Location services, and said that removing SmartByte or switching Location off stopped the growth on their PCs. Any app that keeps asking for these permissions could in theory do the same.
If that timeline is right, the bug was public for more than a year before there was a fix.
Watch this step in the video (3:00)
What Microsoft says about it
Microsoft’s support page for KB5095093 lists the update as an optional, non-security preview released on June 23, 2026, for Windows 11 24H2 (build 26100.8737) and 25H2 (build 26200.8737). Its change log has a single line about this problem, filed under Storage: the update “improves disk space usage for the CapabilityAccessManager.db-wal file”. The entry is dated June 29, six days after the update came out.
That is all Microsoft says. It does not name the cause, say how much space the change saves, or say whether a file that has already grown will shrink. The fix was then included in the July 14, 2026 security update, KB5101650 (builds 26200.8875 and 26100.8875), so any Windows 11 24H2 or 25H2 PC that is fully up to date should already have it.
Watch this step in the video (4:28)
Why you should not delete it
Most of the threads online give the same advice: take ownership of the folder, stop the service, delete the file. That is what the Continue button starts, and there are scripts that automate the whole thing. I would not do it.
- People who tried it in the Q&A thread reported Wi-Fi no longer working, screen capture breaking, and one person who could not sign in without an internet connection. Another could not open the folder even in Safe Mode and ended up reinstalling Windows.
- The cause is still there. Several people saw the file grow back within days or weeks, so deleting it only delays the problem.
- The folder is a system folder, and its permissions have been changed by the process. Some people needed extra commands afterwards to reset them.
To be fair, an accepted answer in that thread does describe deleting only the .db-wal file from Safe Mode with the service stopped, and some people said it worked. It also comes with a long list of people for whom it did not go well. Now that Microsoft has shipped a fix, I would try that first and leave the folder alone.
Install the fix and check again
BEFORE YOU UPDATE
Create a restore point first if you like to be careful. Search for “Create a restore point” in Start and click Create. It takes a minute.
- Open Settings > Windows Update and click Check for updates, then install whatever is offered. KB5095093 and the July 2026 update KB5101650 both contain the fix, and so do the monthly updates after them.
- Restart the PC when it asks. An update is not fully applied until you do.
- Click Start, type winver and press Enter. If the build number is 26200.8737 or higher on 25H2, or 26100.8737 or higher on 24H2, the fix is in. You may well be covered already.
If the update does not show up, Microsoft rolls out some updates in waves. Turn on Get the latest updates as soon as they are available at the top of the Windows Update page and check again.
After the restart, open Command Prompt as administrator and run the same robocopy line from earlier. Look at the db-wal line again. If you were affected, the number should be much smaller. Microsoft does not say that the update clears a file that has already grown, so do not take my word or theirs for it. The check tells you what happened on your PC.
If the file is still huge after the update and a restart, I would stop there and ask for help, for example on Microsoft’s Q&A forum. Create a restore point or a backup before anyone, including me, talks you into changing that folder.
Watch this step in the video (6:21)
Questions people ask
Which Windows versions are affected?
The reports and Microsoft’s fix are for Windows 11 versions 24H2 and 25H2. The update builds are 26100.8737 and 26200.8737 or higher.
Is the robocopy command safe?
It only lists files. The /L switch means nothing is copied, changed or deleted. It needs an administrator Command Prompt because the folder is locked.
Is CapabilityAccessManager.db-wal a virus?
No. It is a normal Windows file, a log kept by the service that tracks which apps use your camera, microphone and location. The problem is that it grows too large on some PCs.
Can I just delete the file?
You can find guides that tell you to, and some people report that it worked for them. Others report broken Wi-Fi, broken screen capture and a file that came back. I recommend installing the update first and leaving the folder alone.
How big should the file be?
A few megabytes or less. Mine is 1.4 MB. Hundreds of megabytes, or gigabytes, mean it is affected.
My C drive is full but the file is small. What else could it be?
System & reserved also includes the page file, the hibernation file and restore points. Check Settings > System > Storage for the other categories, and run Disk Cleanup or the Temporary files option. This file is only one possible cause.
Run the check and tell me what number you got in the comments. I am curious how many PCs have this file sitting at several gigabytes without the owner knowing.
