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E_SYNCENGINE_FILE_SYNC_PARTNER_ERROR
The scope of E_SYNCENGINE_FILE_SYNC_PARTNER_ERROR is Windows cloud-file and sync-engine infrastructure: a delegated sync partner failed while owning the file operation. Preserve 0x8802B005 beside the returning call before cleanup or retry creates a more generic secondary failure.
Read the boundary first
When it is returned, a Windows sync engine coordinates local NTFS objects, provider metadata, remote identifiers, quota and naming rules, placeholder hydration, network authentication, and asynchronous upload or download state. During a this result investigation, the same Explorer action can cross several of those boundaries, so diagnosis must retain the first failing stage rather than treating every code as a generic connectivity problem.
During a this result investigation, the primary engine handed responsibility to another program or provider. The outer HRESULT identifies delegation, while the partner’s own status, version and correlation ID carry the actual cause.
The first owner to inspect is the local sync root, placeholder state, file-system operation, provider request, network exchange, account policy, or remote storage operation that produced the HRESULT.
Keep neighboring conditions separate
When it is returned, UNKNOWN_SERVICE_ERROR belongs to the remote service path; PARTNER_ERROR identifies another local sync component.
Do not troubleshoot only the primary engine or retry while two partners claim ownership.
Incident record for this HRESULT
| Capture | Diagnostic value |
|---|---|
| Partner identity and version for it. | This places the failure on the lifecycle or transaction timeline and helps test the Windows cloud-file and sync-engine infrastructure boundary. |
| Delegated operation and file ID for it. | This separates caller input from environment and service state and helps test the Windows cloud-file and sync-engine infrastructure boundary. |
| Partner status and logs for it. | This provides a stable comparison across retries or another machine and helps test the Windows cloud-file and sync-engine infrastructure boundary. |
| Handoff and completion correlation IDs for it. | This identifies the exact object or resource generation involved and helps test the Windows cloud-file and sync-engine infrastructure boundary. |
Reproduce without destroying evidence
The investigation should change one variable at a time and keep the original failing sample.
- First: Confirm which component owns the file.
- Next: Capture the partner result before translation.
- Then: Test the same file without delegation where supported.
- Finally: Verify cleanup of incomplete handoffs.
Three useful controls
- Second supported path for the same stable item: for it, a changed result separates retained object, connection, path, host, or device state from the original input. Hold constant: for it, keep account, remote item version, and client build fixed.
- Reduced failing operation: If this result follows the reduced step, the rejecting transition is localized. Hold constant: for it, retain partner identity and version and remove only unrelated work.
- Targeted corrective control: Use this as a diagnostic branch rather than a blanket workaround: confirm which component owns the file. Hold constant: for it, keep the original this result sample available for the final regression test.
Definition of done
Closure for it requires exactly one partner owns the operation and reports a traceable completion or failure; then repeat the next lifecycle operation to detect stale state.
Technical references
The references below define the API family or storage/protocol behavior used to interpret this result.
- Microsoft: Build a Cloud Files sync engine
- Microsoft: Cloud Filter API reference
- Microsoft: Determine cloud placeholder state
- Microsoft: Restrictions and limitations in OneDrive and SharePoint
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