WebSocket 1006 Abnormal Closure vs 1009 Message Too Big
Both WebSocket 1006 (Abnormal Closure) and 1009 (Message Too Big) belong to the WebSocket Close Codes category. 1006 indicates that a reserved value indicating the connection was closed abnormally without a Close frame being sent. This code must not be set by an endpoint. Meanwhile, 1009 means that an endpoint is terminating the connection because it received a message that is too large for it to process.
説明
A reserved value indicating the connection was closed abnormally without a Close frame being sent. This code must not be set by an endpoint.
このコードが表示される場合
The TCP connection dropped unexpectedly — the server crashed, the network cable was unplugged, or a firewall killed the idle connection. No proper WebSocket Close handshake occurred.
解決方法
Implement reconnection with exponential backoff. Use WebSocket ping/pong frames to detect dead connections early. Check for network-level timeouts or aggressive load balancer idle limits.
説明
An endpoint is terminating the connection because it received a message that is too large for it to process.
このコードが表示される場合
The message payload exceeded the server's configured maximum frame or message size limit. Common when uploading large files or sending huge JSON payloads over WebSocket.
解決方法
Reduce the message size by chunking large payloads into smaller frames. Alternatively, increase the server's max message size configuration if the large payload is expected.
主な違い
WebSocket 1006: A reserved value indicating the connection was closed abnormally without a Close frame being sent. This code must not be set by an endpoint.
WebSocket 1009: An endpoint is terminating the connection because it received a message that is too large for it to process.
You encounter 1006 when the TCP connection dropped unexpectedly — the server crashed, the network cable was unplugged, or a firewall killed the idle connection. No proper WebSocket Close handshake occurred.
You encounter 1009 when the message payload exceeded the server's configured maximum frame or message size limit. Common when uploading large files or sending huge JSON payloads over WebSocket.
どちらをいつ使うか
For 1006 (Abnormal Closure): Implement reconnection with exponential backoff. Use WebSocket ping/pong frames to detect dead connections early. Check for network-level timeouts or aggressive load balancer idle limits. For 1009 (Message Too Big): Reduce the message size by chunking large payloads into smaller frames. Alternatively, increase the server's max message size configuration if the large payload is expected.