Troubleshooting

The viewer does not open

Check the collector process and curl http://127.0.0.1:19877/health on its host. The default listener is loopback. Use an SSH tunnel for remote access or explicitly configure a read-only private listener. Capture being OFF does not stop the viewer.

No native details in an old event

Schema-1 events lack native state. Install the current module and record a new short capture. Historical values cannot be reconstructed.

Capture is active but no events arrive

Check matching UDP port, matching control path, worker read permissions and sampling/location settings. The control file must exist before workers map it. Check /health for invalid, queue-dropped, storage-dropped or inactive-dropped counters. Long-lived requests only emit at completion.

nginx rejects the module

Compare nginx -V with the exact module build source/configuration, architecture and distribution patches. Do not force an ABI-incompatible shared object into nginx. Restore the previous module and validate configuration before any reload.

A request is absent after Stop

The gate is checked again at log. A request that finishes outside the capture window is not emitted. UDP, serialization caps, sampling and collector pressure can also lose observation records. Request processing does not depend on event delivery.