The short version
- 01Record the update package and the time error 0x80070020 appears.
- 02Match the CBS.log error to the file being accessed during installation.
- 03Use Microsoft's clean-boot comparison with administrator guidance if appropriate.
- 04Restore normal startup after completing the clean-boot comparison.
- 05Have support capture Process Monitor events and filter for the file named in CBS.log.
- 06Resolve the identified process or filter conflict and retry the same update.
Raw message
0x80070020 — ERROR_SHARING_VIOLATION
Likely causes
- A required file has an incompatible sharing or access state during the update.
- A non-Microsoft filter driver or another process can be involved; log analysis identifies the specific conflict.
Treat a clean boot as a temporary comparison
Microsoft links a clean boot to investigate background interference. Its procedure hides Microsoft services, tracks disabled startup entries and restores normal startup after testing. On a managed PC, ask the administrator to perform that comparison; do not change advanced boot options as part of a routine update repair.
Capture the conflict before changing its owner
Microsoft's deeper procedure captures an update attempt in Process Monitor, stops capture and filters for the filename from CBS.log. Use the official Sysinternals tool and retain the capture for support. Our recommendation is to repair the identified process or filter with its owner rather than assume every security product must be removed.
Sources and review notes
Checked on . Based on Microsoft's sharing-violation investigation, clean-boot procedure and official Process Monitor page. Matching attempts and targeted administrator review are editorial guidance. Complete logs and captures can contain device details and should follow the support channel's sharing instructions. Glitchary is independent of Microsoft.