n8n-io/n8n · error · Error

Failed to create new tab

Error message

Failed to create new tab

What it means

Thrown by AgentBrowserAdapter.newPage when, after running `tab new` and refreshing tabs, there is no active tab AND the tabs array is empty (so the last-element fallback also fails). The literal message is a plain Error (not an McpBrowserError subclass). This indicates the `agent-browser` CLI accepted the tab-new command but produced no tab — a session-level inconsistency.

Source

Thrown at packages/@n8n/mcp-browser/src/adapters/agent-browser.ts:274

	async listTabs(): Promise<PageInfo[]> {
		return (await this.refreshTabs()).map((t) => ({ id: t.tabId, title: t.title, url: t.url }));
	}

	async listTabSessionIds(): Promise<string[]> {
		return await Promise.resolve(this.tabCache.map((t) => t.tabId));
	}

	async listTabIds(): Promise<string[]> {
		return (await this.listTabs()).map((t) => t.id);
	}

	async newPage(url?: string): Promise<PageInfo> {
		if (url) AgentBrowserAdapter.assertSafeArg(url, 'URL');
		await this.run(['tab', 'new', ...(url ? [url] : [])]);
		const tabs = await this.refreshTabs();
		const active = tabs.find((t) => t.active) ?? tabs[tabs.length - 1];
		if (!active) throw new Error('Failed to create new tab');
		return { id: active.tabId, title: active.title, url: active.url };
	}

	async closePage(pageId: string): Promise<void> {
		await this.switchToTab(pageId);
		await this.run(['tab', 'close']);
		this.tabCache = this.tabCache.filter((t) => t.tabId !== pageId);
		this.urlCache.delete(pageId);
	}

	async focusPage(pageId: string): Promise<void> {
		await this.switchToTab(pageId);
	}

	// =========================================================================
	// Navigation
	// =========================================================================

View on GitHub (pinned to 5ac6606e81)

Solutions

1. Call adapter.close() then adapter.launch(config) again to reset the session, then retry newPage.
2. Check the gateway logs for a relay disconnect or extension disconnect around the same time.
3. Verify only one gateway/agent-browser session is using the SESSION_NAME 'n8n-computer-use'.
4. Run `agent-browser --session n8n-computer-use tab list` manually to inspect session state.

Example fix

// before
const page = await adapter.newPage(url);

// after — reset session on failure
async function robustNewPage(adapter, config, url) {
  try {
    return await adapter.newPage(url);
  } catch (err) {
    if (/Failed to create new tab/.test(err.message)) {
      await adapter.close();
      await adapter.launch(config);
      return await adapter.newPage(url);
    }
    throw err;
  }
}

function isNewTabFailure(error: unknown): boolean {
  return error instanceof Error && /Failed to create new tab/.test(error.message);
}

try {
  return await adapter.newPage(url);
} catch (err) {
  if (isNewTabFailure(err)) {
    await adapter.close();
    await adapter.launch(config);
    return await adapter.newPage(url);
  }
  throw err;
}

When it happens

Trigger: Calling adapter.newPage(url?) — the run(['tab', 'new', ...]) call does not throw, but the subsequent refreshTabs() returns an empty array, so `tabs.find(t => t.active)` is undefined and `tabs[tabs.length - 1]` is also undefined.

Common situations: The agent-browser session is in a bad state (no browser window attached); the browser crashed between the tab-new command and the tab-list refresh; a CDP/relay disconnect happened mid-operation; the session name collided and the new tab landed in a different session.

Related errors

• Page not found: ${pageId}
• agent-browser failed
• Invalid ${role}: argument cannot start with '-' (got: ${JSON
• agent-browser action failed
• No executable path for ${browser}

AI-assisted analysis of n8n-io/n8n@5ac6606e81 (2026-08-12). Data as JSON: /api/errors/991074bcea1fc9af. Report an issue: GitHub.