| Previous | Next |
| E_SYNCENGINE_SYNC_PAUSED_BY_SERVICE | E_SYNCENGINE_SERVICE_AUTHENTICATION_FAILED |
E_SYNCENGINE_FILE_IDENTIFIER_UNKNOWN
E_SYNCENGINE_FILE_IDENTIFIER_UNKNOWN belongs to Windows cloud-file and sync-engine infrastructure. It marks the engine cannot resolve the file’s expected local-to-remote identifier mapping. The useful starting point is the exact API, object and state transition that returned 0x8802C002, because a shell or application message can hide that boundary.
Where this result is raised
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., 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.
When it is returned, names and paths are not stable identities across rename, move and conflict resolution. During a this result investigation, a missing mapping can reflect stale metadata, a deleted remote item, or a local placeholder whose provider identity was lost.
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.
Evidence worth collecting
- Local file ID and placeholder identity. for it, this pins the event to an object or resource generation within the Windows cloud-file and sync-engine infrastructure boundary.
- Remote item ID. for it, this places the event on the lifecycle or transaction timeline within the Windows cloud-file and sync-engine infrastructure boundary.
- Rename/move history. for it, this separates caller input from environment and service state within the Windows cloud-file and sync-engine infrastructure boundary.
- Provider metadata and tombstone state. for it, this creates a stable comparison across retries or another machine within the Windows cloud-file and sync-engine infrastructure boundary.
A controlled diagnostic sequence
During a this result investigation, reduce the case while preserving the condition described by the HRESULT.
- First: Query placeholder/provider identity.
- Next: Reconcile by stable IDs, not only path.
- Then: Check remote deletion or replacement.
- Finally: Avoid assigning a new ID before conflict analysis.
How to interpret comparison tests
| Control | Interpretation | Hold constant |
|---|---|---|
| Same input, fresh object or connection | If the result disappears, retained lifecycle or ownership state is implicated. | While diagnosing this result, keep the original data, account, device, or timeline parameters unchanged. |
| Same object, reduced operation | If the result follows one specific transition, statement, file, or ceremony step, the failure is localized. | While diagnosing this result, remove only unrelated work and keep the first failing boundary visible. |
| Same stable item ID, second supported path | A change separates local file-system/provider state from remote service state. | While diagnosing it, keep account, remote version and client build fixed. |
What this code does not justify
FILE_NOT_UPLOADED can lack a committed remote version; IDENTIFIER_UNKNOWN means the mapping expected by the engine cannot be resolved.
Do not match by filename alone and attach the item to an unrelated remote object.
Verification after correction
Treat it as corrected only when rename, move, delete and recreate tests maintain correct identity or produce an explicit conflict; retain the original negative case so fallback cannot be mistaken for repair.
Technical references
The references below define the API family or storage/protocol behavior used to interpret it.
- 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
Looking for a different code? Search another status or error code.