# 16022: Conference does not exist or is completed

Log Level: ERROR

## Description

This error occurs when a request targets a conference that does not exist or is no longer active. Conference participant operations work only with active conferences, and a request fails when the specified `ConferenceSid` is not active.

### Possible causes

* You submitted a `ConferenceSid` that does not belong to an active conference. Requests against a non-active conference fail.
* The conference ended before the request completed. A conference ends when the last participant leaves or when a participant with `endConferenceOnExit="true"` leaves.
* You tried to retrieve or update participants after the conference reached `completed` status. Participant resources are available only for active conferences.

### Possible solutions

* Confirm that the conference is still active before you add, retrieve, update, or remove participants. If you use `FriendlyName`, create the conference by adding the first participant with that name.
* Make participant requests before the conference ends. Do not reuse a completed conference for additional participant operations.
* Use `statusCallback` and `statusCallbackEvent` to watch for conference lifecycle events, including `end`, and stop participant actions once the conference is over.

#### Additional resources

* [Conferences Participants subresource](/docs/voice/api/conference-participant-resource)
* [TwiML Voice: `<Conference>`](/docs/voice/twiml/conference)