When trying to screenshot, test, or automate interactions with a local HTML file via Playwright (including Playwright MCP), navigating to file:// URLs fails with a security error or the page loads blank. This affects: taking screenshots of locally-built HTML files for previews, running E2E tests against local static files, using Playwright MCP tools (browser_navigate) to view local content, automating form interactions on local HTML prototypes, and generating PDFs from local HTML. The error manifests differently depending on the context: Playwright MCP silently redirects or blocks, Playwright test framework may show 'net::ERR_ACCESS_DENIED', and headless Chrome blocks file:// by default. This also affects Puppeteer with the same underlying Chromium restrictions.

Python curses-based TUI apps (using curses.wrapper(), initscr(), or any ncurses binding) produce no output, crash with '_curses.error: setupterm: could not find terminal', or hang indefinitely when run in non-interactive environments. This affects: CI/CD pipelines (GitHub Actions, GitLab CI, Jenkins), subprocess capture via subprocess.run() or subprocess.Popen(), piped output (python app.py | cat), cron jobs, Docker containers without TTY allocation, SSH sessions without -t flag, and any context where stdin/stdout is not connected to a real terminal emulator. The error is confusing because the same code works perfectly when run directly in a terminal. Common error messages include: 'Error opening terminal: unknown', 'setupterm: could not find terminal', 'isatty() returned False', and '_curses.error: cbreak() returned ERR'.