--- "@context": https://schema.org "@type": TechArticle "@id": https://www.twilio.com/docs/api/errors/31921#article headline: "31921: Stream - WebSocket - Close Error" url: https://www.twilio.com/docs/api/errors/31921 inLanguage: en dateModified: 2026-06-08T11:38:30.000Z author: "@type": Organization name: Twilio Developer Education Team publisher: "@type": Organization name: Twilio --- # 31921: Stream - WebSocket - Close Error Log Type: APPLICATION Log Level: ERROR ## Description This error occurs when Twilio establishes a Media Streams WebSocket connection to your server and your server then closes that connection. In bidirectional Media Streams, closing the WebSocket from your server stops the Stream. ### Possible causes * Your WebSocket server ended the connection and Twilio received a WebSocket close event. * Your application closed the WebSocket for a bidirectional Stream started with ``. Twilio resumes the remaining TwiML only after your server closes the WebSocket connection. * The WebSocket connection associated with the Media Stream was closed by your server before you intended the Stream to end. Each Media Stream uses a single WebSocket connection. ### Possible solutions * Review your WebSocket server logs to identify the close code and the condition that caused the server to end the connection. * If you use bidirectional Media Streams with ``, keep the WebSocket connection open for as long as you want the Stream to continue. Close it only when you intend to stop the Stream. * Add a `statusCallback` URL to `` so Twilio sends `stream-started`, `stream-stopped`, and `stream-error` events. Use the `StreamError` value in that callback to capture more detail about the failure. * Make sure your Media Streams application accepts secure WebSocket connections from Twilio on TCP port 443. #### Additional resources * [Media Streams Overview](/docs/voice/media-streams) * [WebSocket Messages for Media Streams](/docs/voice/media-streams/websocket-messages) * [TwiML `` Reference](/docs/voice/twiml/stream)