microsoft/playwright · error · Error

Not supported

Error message

Not supported

What it means

WVBrowser (the iOS Safari / WKWebView connection via ios_webkit_debug_proxy) exposes a single pre-existing browser context tied to the live Safari process. It cannot manufacture a fresh context because the underlying device only exposes whatever Safari is running. doCreateNewContext therefore unconditionally throws 'Not supported'.

Source

Thrown at packages/playwright-core/src/server/webkit/webview/wvBrowser.ts:271

    entry.connection.close();
    entry.page.didClose();
  }

  async _closeAllTabs(): Promise<void> {
    for (const pageId of Array.from(this._tabs.keys()))
      this._detachTab(pageId);
    this._fireDidCloseOnce();
  }

  private _fireDidCloseOnce(): void {
    if (this._didCloseFired)
      return;
    this._didCloseFired = true;
    this.didClose();
  }

  async doCreateNewContext(options: types.BrowserContextOptions): Promise<BrowserContext> {
    throw new Error('Not supported');
  }

  contexts(): BrowserContext[] {
    return [this._context];
  }

  version(): string {
    return '';
  }

  userAgent(): string {
    return '';
  }

  isConnected(): boolean {
    return this._tabs.size > 0;
  }
}

View on GitHub (pinned to c8fc3bf8d3)

Solutions

1. Use browser.contexts()[0] (the existing WVBrowserContext) instead of browser.newContext().
2. If you need isolation, disconnect and reconnect rather than creating a context.
3. Restructure tests so each test does not call newContext on a webview browser.

Example fix

// before
const browser = await webkit.connectOverCDP(endpoint);
const context = await browser.newContext(); // Not supported

// after
const browser = await webkit.connectOverCDP(endpoint);
const context = browser.contexts()[0];

function useExistingContext(browser) {
  const contexts = browser.contexts();
  if (!contexts.length) throw new Error('No context attached to webview browser');
  return contexts[0];
}
const context = useExistingContext(browser); // instead of browser.newContext()

let context;
try { context = await browser.newContext(); }
catch (e) {
  if (/Not supported/i.test(String(e.message))) context = browser.contexts()[0];
  else throw e;
}

When it happens

Trigger: Calling browser.newContext() (or any path that triggers doCreateNewContext) on a browser obtained from webkit.connectOverCDP against a real iOS Safari session. The webview backend has exactly one context.

Common situations: Treating a connectOverCDP webview browser like a launched browser and trying to spin isolated contexts; test code reused from a chromium launch flow that calls newContext per test.

Related errors

• ios_webkit_debug_proxy ${proxyBase}/json returned ${res.stat
• No Mobile Safari tabs found at ${this._proxyBase}/json — ope
• Cannot set cookies without an open page
• Method not implemented.
• SyncServer: failed to bind HTTP server

AI-assisted analysis of microsoft/playwright@c8fc3bf8d3 (2026-08-12). Data as JSON: /api/errors/4f6e6adea9421896. Report an issue: GitHub.