Playwright MCP browser_evaluate Hangs? The CSP Sandbox Bug Explained

Playwright MCP version 0.0.84 can indefinitely hang after a successful navigation when its post-action “settle” delay relies on a page-side setTimeout that cannot run, particularly in Chromium on pages served with a Content-Security-Policy sandbox directive such as raw.githubusercontent.com, or when the Playwright page clock is paused. The issue affects tools sharing the same completion path, including browser_evaluate, browser_click, browser_press_key, and browser_run_code_unsafe, while browser_navigate generally still returns. Testing reported that Firefox handled the CSP-sandbox case normally, although paused clocks reportedly affect all major engines, and setting the settle timeout to zero does not resolve the problem because it still schedules a timer. As of November 1, 2026, an approved but unmerged fix proposed adding a Node-side deadline so completion no longer depends solely on page timers. Until a release includes that change, suggested mitigations include applying client-side per-call deadlines, navigating away after a stalled call, using Firefox for sandboxed pages, resuming paused clocks before further MCP actions, and retrieving static content through direct HTTP requests or scraping tools rather than a browser session.

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