CBS.log & Windows Logs CBS Folder

Bottom Line: It is completely safe to delete CBS.log and compressed log files in the C:\Windows\Logs\CBS folder. Deleting these log files will not affect Windows operations, performance, or system updates.

What is the CBS.log File?

Located at C:\Windows\Logs\CBS\CBS.log, this file contains logs generated by Component-Based Servicing-packages)-packages)-packages)-packages)-packages)-packages)-packages) (CBS).

Windows writes to this log file whenever:

• Windows Update installs or updates system components.
• You run system repair tools like System File Checker (sfc /scannow).
• Windows DISM servicing commands execute.

The Infamous CBS Log Bug

Normally, CBS.log is small (a few megabytes). However, a well-known Windows bug occurs when CBS.log reaches 2 GB in size. The Windows Makecab utility attempts to compress it into CbsPersist_xxxx.cab files, fails, and gets stuck in a loop—creating dozens of gigabytes of useless log files that fill up drive C:.

Can You Delete CBS.log?

✅ Yes, it is completely safe to delete.

• No system risk: CBS files are plain text diagnostic logs.
• Frees massive disk space: If your system hit the CBS logging bug, deleting these files can reclaim 10 GB to 50 GB+ of drive space immediately.

How to Delete CBS.log

Because Windows continuously logs background events, CBS.log may currently be locked by the Windows Modules Installer-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder)-folder) service (TrustedInstaller).

Method 1: Delete via Windows Command Prompt

1. Open Start, search for cmd, right-click Command Prompt, and select Run as administrator.
2. Stop the Windows Modules Installer service:

   net stop msiserver
   net stop TrustedInstaller

3. Delete the log files:

   del /f /q C:\Windows\Logs\CBS\*.*

4. Restart the service (or simply reboot your computer):

   net start TrustedInstaller

Method 2: Manual Deletion in File Explorer

1. Navigate to C:\Windows\Logs\CBS.
2. Delete all .cab and .log files (such as CbsPersist_xxxx.log or CbsPersist_xxxx.cab).
3. If CBS.log says “File in use”, skip that single active file and delete all the old CbsPersist files.

Related Guides

• Learn about deleting dumpstack.log.
• How to clean up SoftwareDistribution Download files.
• Understand the WinSxS Component Store.