What does Windows error code 550 (ERROR_PROFILING_NOT_STARTED) mean?

ERROR_PROFILING_NOT_STARTED

What ERROR_PROFILING_NOT_STARTED means

This status is returned when code attempts to stop, query, or otherwise operate on a profiling session that was never started, has already ended, or was created in a different scope. It is primarily a sequencing error rather than evidence that the profiler itself is damaged.

Where it commonly appears

• Performance-analysis tools that start and stop kernel or process profiling sessions
• Diagnostic agents that expose profiling through a service or RPC boundary
• Cleanup paths that run after partial initialization and assume a session exists

Likely causes

• The start operation failed but the failure was ignored
• A stop or query call was issued twice
• The session handle belongs to another process, target, or boot session
• Concurrent cleanup raced with normal shutdown

Troubleshooting checklist

1. Log the result of the original start call and retain the first failure
2. Record the session identifier, target process, caller PID, and start/stop timestamps
3. Check whether cleanup can run from more than one thread
4. Verify that a restart or service reconnect did not discard the in-memory session state

Guidance for developers

Model profiling as an explicit state machine: not started, active, stopping, and stopped. Transition to active only after the start call succeeds. Make cleanup idempotent, and do not overwrite the original initialization failure with this secondary status.

Guidance for administrators

If this appears in a third-party profiler, restart the profiling session rather than repeatedly issuing stop or query commands. Collect the profiler log and the first error before restarting the service.

Example

A monitoring service allocates its bookkeeping object, fails to enable profiling because access is denied, and later executes a generic shutdown routine. The shutdown routine calls the stop API and receives this code. The actionable failure is the earlier access-denied result, not the shutdown status.

Related conditions

Do not confuse this with ERROR_PROFILING_NOT_STOPPED, which means an active profiling operation could not be stopped, or ERROR_PROFILING_AT_LIMIT, which means a resource limit prevented another profile from starting.

References

• Microsoft system error codes 500–999
• Event Tracing and performance diagnostics