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UTC_E_TOGGLE_TRACE_STARTED
Where the UTC workflow stopped: alternative trace request
UTC_E_TOGGLE_TRACE_STARTED (0x87C51001) is a Universal Telemetry Client result from the ETW trace-session control layer. The key question is which UTC object rejected the request. The relevant state is alternative trace request: the toggle request started an alternative trace rather than reporting an unsuccessful start. This identifies a specific UTC/DiagTrack condition, not a general service failure.
Evidence to preserve
| UTC diagnostic field | Value |
|---|---|
| Producing layer | ETW trace-session control |
| Owning state or object | alternative trace request |
| Evidence to collect | requested profile, prior session name, trace priority, start timestamp and returned session identity |
| Narrow comparison | issue the same toggle with no active matching session, then with the alternative session already active |
| Do not confuse with | UTC_E_TRACE_NOT_RUNNING concerns a stop or update request for a session that is absent |
Controlled reproduction
- Capture requested profile, prior session name, trace priority, start timestamp and returned session identity. Do this before restarting the service or deleting any working directory.
- Perform this one-variable comparison: issue the same toggle with no active matching session, then with the alternative session already active.
Nearby result: UTC_E_TRACE_NOT_RUNNING — concerns a stop or update request for a session that is absent.
Trace-session note
Use an ETW controller view to list session name, GUID, mode, buffers and enabled providers while this result is active. The presence of an ETL file from an earlier run is not proof that the required in-memory session currently exists or is owned by UTC.
Correction and verification
Treat the result as state feedback, retain the returned session identity and avoid starting a duplicate controller.
Technical references
- Microsoft Open Specifications: Windows error-code registry — reference for ETW trace-session control while interpreting this result.
- Microsoft: Universal Telemetry Client configuration diagnosis — reference for ETW trace-session control while interpreting it.
- Microsoft: Event Tracing for Windows
- Microsoft: WPR and ETW sessions
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