What causes "WebSocket is closed" in siyuan-note/siyuan?

Create a new socket via client.socket.connect(path) and open that instead of reopening the closed instance.

WebSocket is closed

Error message

WebSocket is closed

What it means

The WebSocket has already fully closed (ready state = CLOSED) when open() was called on it. A closed goja-backed socket instance cannot be reopened; the binding rejects immediately rather than queueing an open promise that could never resolve.

Solutions

Create a new socket via client.socket.connect(path) and open that instead of reopening the closed instance.
Track the onclose event and rebuild the socket in that handler.
Before open(), check readyState === 3 and replace the socket object.

Example fix

// before
if (socket.readyState === 3) { socket.open(); } // rejects
// after
if (socket.readyState === 3) {
  socket = client.socket.connect('/ws');
  socket.open();
}

Defensive patterns

Strategy: type-guard

Validate before calling

if (socket.readyState === 3) { socket = client.socket.connect(path); }

Type guard

const isOpenable = (s) => s.readyState !== 2 && s.readyState !== 3; // or: recreate if CLOSED

Try / catch

try {
  socket.open();
} catch (e) {
  if (String(e).includes('WebSocket is closed')) {
    socket = client.socket.connect(path);
    socket.open();
  }
}

Prevention

Treat socket instances as single-use: recreate after close
Listen for onclose and rebuild the socket there
Clear reconnect timers that reference stale socket objects

When it happens

Trigger: Calling socket.open() on a socket whose connection already terminated — after onclose fired, after the kernel shut down, or after an explicit close() completed.

Common situations: Reconnect timers firing on a stale socket object; plugin suspends/resumes where the socket closed in the background; kernel restart killing all connections.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of siyuan-note/siyuan@9f775e8a12 (2026-09-19). Data as JSON: /api/errors/cc2a9dcfed776e5a. Report an issue: GitHub.

Appendix: source

Thrown at kernel/plugin/api_client.go:338

				})
			}

			ws_open := rt.ToValue(func(openCall goja.FunctionCall, rt *goja.Runtime) goja.Value {
				openPromise, openResolve, openReject := rt.NewPromise()

				openRunErr := p.worker.Run(func(rt *goja.Runtime) (_ any, err error) {
					state := WebSocketState(readyState.Load())
					switch state {
					case WebSocketReadyStateOpen:
						if resolveErr := openResolve(nil); resolveErr != nil {
							logging.LogErrorf("[plugin:%s] siyuan.client.socket.open resolve: %v", p.Name, resolveErr)
						}
						return
					case WebSocketReadyStateClosing:
						err = fmt.Errorf("WebSocket is closing")
						return
					case WebSocketReadyStateClosed:
						err = fmt.Errorf("WebSocket is closed")
						return
					}

					addOpenPromise(openResolve, openReject)
					openOnce.Do(func() {
						go func() {
							conn, _, dialErr := gws.NewClient(h, &gws.ClientOption{
								Addr:          wsURL,
								RequestHeader: wsHeader,
							})
							if dialErr != nil {
								p.worker.Run(func(rt *goja.Runtime) (_ any, _ error) {
									setReadyState(rt, WebSocketReadyStateClosed)

									event := rt.NewObject()
									event.Set("type", rt.ToValue("error"))
									event.Set("error", rt.NewGoError(dialErr))
									invokeHook(rt, "onerror", event)

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