| Previous | Next |
| ERROR_ENVVAR_NOT_FOUND | ERROR_FILENAME_EXCED_RANGE |
ERROR_NO_SIGNAL_SENT
What ERROR_NO_SIGNAL_SENT means
No process in the addressed command subtree had an eligible signal handler, so the signal was not delivered. This is a legacy process-tree signaling result. The target group or subtree was found, but none of its processes could receive the requested signal through the expected handler mechanism.
Common causes
- No process registered a handler for the signal
- The intended target is outside the selected subtree
- Handlers were removed during shutdown
- The signal number or execution mode is incompatible with the targets
How to investigate
- Enumerate the command subtree and registered handlers
- Verify the group or tree selector used by the sender
- Record handler registration and removal events
- Send to one known target to isolate tree selection from handler availability
Developer guidance
Use an explicit IPC control channel for critical operations. Signals should not be the sole shutdown mechanism when delivery depends on optional handlers.
Administrator and support guidance
Confirm that the correct session and process tree are being controlled. Do not broaden permissions until target selection is verified.
How this code differs from related results
ERROR_SIGNAL_REFUSED indicates rejection by a target; here no eligible handler received the signal at all.
Evidence worth collecting
For ERROR_NO_SIGNAL_SENT, begin the trace at the operation where no process registered a handler for the signal. For ERROR_NO_SIGNAL_SENT, preserve the exact API boundary, numeric result, process and thread identifiers, relevant object state, and the component version. The first verification point should be to enumerate the command subtree and registered handlers. This evidence distinguishes the specific ERROR_NO_SIGNAL_SENT contract from a later secondary failure.
Recovery and verification
Recovery for ERROR_NO_SIGNAL_SENT should address the observed condition rather than merely retrying the same call. After the change, reproduce the scenario in which no process registered a handler for the signal, then confirm that the intended operation completes and that cleanup returns all associated resources. For ERROR_NO_SIGNAL_SENT, also verify that the next repeated operation follows the same successful path without increasing the resource class implicated by this result.
When to escalate
Escalate ERROR_NO_SIGNAL_SENT with a minimal reproduction focused on the failing process-control boundary. Include the operating-system build, binary architecture, runtime or compatibility-layer version, the exact input values, and a timestamped trace showing no process registered a handler for the signal. For the ERROR_NO_SIGNAL_SENT escalation record, note whether changing concurrency, object lifetime, target process, module set, or endpoint location alters the result.
References
Looking for a different code? Search another status or error code.