WebSocket 1006 Abnormal Closure vs 1012 Service Restart
Both WebSocket 1006 (Abnormal Closure) and 1012 (Service Restart) 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, 1012 means that the server is terminating the connection because it is restarting. The client should reconnect after a brief delay.
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
The server is terminating the connection because it is restarting. The client should reconnect after a brief delay.
このコードが表示される場合
The server is performing a planned restart — for example, during a deployment or configuration reload. The connection will be available again shortly.
解決方法
Implement automatic reconnection with a short delay (1-5 seconds). This code signals that reconnecting is expected and should succeed once the server is back up.
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 1012: The server is terminating the connection because it is restarting. The client should reconnect after a brief delay.
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 1012 when the server is performing a planned restart — for example, during a deployment or configuration reload. The connection will be available again shortly.
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 1012 (Service Restart): Implement automatic reconnection with a short delay (1-5 seconds). This code signals that reconnecting is expected and should succeed once the server is back up.