microsoft/playwright · error · Error

connectToServer must be called on the page-side WebSocketRou

Error message

connectToServer must be called on the page-side WebSocketRoute

What it means

Error "connectToServer must be called on the page-side WebSocketRoute" thrown in microsoft/playwright.

Source

Thrown at packages/playwright-core/src/client/network.ts:485

  private _onServerMessage?: (message: string | Buffer) => any;
  private _onServerClose?: (code: number | undefined, reason: string | undefined) => any;
  private _server: api.WebSocketRoute;
  private _connected = false;

  constructor(parent: ChannelOwner, type: string, guid: string, initializer: channels.WebSocketRouteInitializer) {
    super(parent, type, guid, initializer);

    this._server = {
      onMessage: (handler: (message: string | Buffer) => any) => {
        this._onServerMessage = handler;
      },

      onClose: (handler: (code: number | undefined, reason: string | undefined) => any) => {
        this._onServerClose = handler;
      },

      connectToServer: () => {
        throw new Error(`connectToServer must be called on the page-side WebSocketRoute`);
      },

      url: () => {
        return this._initializer.url;
      },

      protocols: () => {
        return [...this._initializer.protocols];
      },

      close: async (options: { code?: number, reason?: string } = {}) => {
        await this._channel.closeServer({ ...options, wasClean: true }, kNoTimeout).catch(() => {});
      },

      send: (message: string | Buffer) => {
        if (isString(message))
          this._channel.sendToServer({ message, isBase64: false }, kNoTimeout).catch(() => {});
        else

View on GitHub (pinned to c8fc3bf8d3)

When it happens

Trigger: Thrown at packages/playwright-core/src/client/network.ts:485 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of microsoft/playwright@c8fc3bf8d3 (2026-08-12). Data as JSON: /api/errors/51263a7bb7991c70. Report an issue: GitHub.