What does Windows error code 551 (ERROR_PROFILING_NOT_STOPPED) mean?

ERROR_PROFILING_NOT_STOPPED

What ERROR_PROFILING_NOT_STOPPED means

The code indicates that a profiling facility still considers the session active after a stop request. Unlike a harmless duplicate stop, this condition can leave counters, callbacks, or kernel resources attached until the owner exits or performs a successful cleanup.

Where it commonly appears

• Sampling profilers and performance counters
• Long-running diagnostic services
• Automated test harnesses that start and stop profiling around each case

Likely causes

• The target is still executing in a state that prevents immediate teardown
• The stop request used stale or mismatched session parameters
• A driver or provider did not acknowledge shutdown
• Another thread changed the profiling state concurrently

Troubleshooting checklist

1. Capture the start parameters and exact stop parameters side by side
2. Check whether the target process exited or changed identity during the session
3. Inspect provider, driver, and service logs for teardown timeouts
4. Determine whether the session remains visible to the profiling tool after the failure

Guidance for developers

Treat failure to stop as a cleanup failure that deserves telemetry, but preserve the primary operation result. Avoid immediately starting another session with the same identifiers. Apply a bounded retry only when the API documentation permits it and the state can be rechecked.

Guidance for administrators

Close the owning profiler cleanly before restarting dependent services. If a kernel component remains attached, a service restart or system restart may be required, but collect logs first because the restart destroys useful evidence.

Example

A test runner ends a benchmark while the profiler provider is still flushing data. The first stop request returns this status. Waiting for the provider-completion event and issuing one documented retry succeeds; issuing repeated blind stop calls only obscures the timing problem.

Related conditions

This differs from ERROR_PROFILING_NOT_STARTED, where no active session exists, and from a generic timeout, which does not necessarily describe profiling state.

References

• Microsoft system error codes 500–999
• Windows performance toolkit