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

Create a new connection via siyuan.client.socket(path) and open() that, rather than reopening the closed one.

WebSocket is closed

Error message

WebSocket is closed

What it means

Returned by socket.open() when readyState is CLOSED (3). The connection has finished closing; open() will not transition it back to open.

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)

View on GitHub (pinned to 251596fc0d)

Solutions

Create a new connection via siyuan.client.socket(path) and open() that, rather than reopening the closed one.
Check readyState === CLOSED and branch to recreate.

Example fix

// before
// ws is already closed
await ws.open(); // rejects: WebSocket is closed
// after
const ws = await siyuan.client.socket('/ws/foo');
await ws.open();

Defensive patterns

Strategy: validation

Validate before calling

if (ws.readyState === 3) {
  ws = await siyuan.client.socket(path); // recreate
}
await ws.open();

Type guard

const isClosed = (ws) => ws.readyState === 3;

Try / catch

try { await ws.open(); }
catch (e) { if (/WebSocket is closed/.test(String(e))) { ws = await siyuan.client.socket(path); await ws.open(); } }

Prevention

Never reopen a closed socket; recreate it.
Track readyState in your connection manager.

When it happens

Trigger: Calling open() on a socket whose close handshake completed, or after the dial failed and readyState was set to CLOSED.

Common situations: Reconnect logic that calls open() on the original socket object instead of creating a new one; or calling open() after a failed dial.

Related errors

AI-assisted analysis of siyuan-note/siyuan@251596fc0d (2026-08-12). Data as JSON: /api/errors/cc2a9dcfed776e5a. Report an issue: GitHub.