Root Cause Diagnosis Turnstile re-issues the challenge when the browser’s signals fail its risk check, so the widget spins or reloads indefinitely instead of returning a token. The usual failing signals are navigator.webdriver === true, a HeadlessChrome user agent, a SwiftShader/software WebGL renderer, missing window.chrome and plugin objects, CDP side effects such as Runtime.enable, and … Read more
Root Cause Diagnosis NoSuchWindowException: no such window: target window already closed from unknown error: web view not found means the driver sent a command to a browsing context that no longer exists. When an alert’s accept() or dismiss() triggers window.close() (or the popup hosting the alert closes itself), the driver’s current-window pointer still references the … Read more
Root Cause Diagnosis A sqlite3.Connection opened before multiprocessing forks the workers is inherited by every child, and SQLite’s POSIX advisory locks belong to the process rather than the connection. A child that closes or garbage-collects the inherited file descriptor releases locks the parent still believes it holds, and can leave the shared lock state inconsistent, … Read more
Root Cause Diagnosis Chromium’s cookie store only writes cookies with an explicit Expires or Max-Age attribute to the on-disk Cookies SQLite database inside the user_data_dir. Cookies issued without either attribute are, per RFC 6265, session cookies — Chromium keeps them in memory only and deliberately purges them on a clean shutdown, regardless of whether you … Read more
Root Cause Diagnosis cv2.VideoCapture() returns an object whose isOpened() is False (and read() returns (False, None)) when no OpenCV backend can open the source. On a headless Linux server this usually happens for one of four reasons: the source does not exist (no /dev/video* node, or the device is not passed into the container or … Read more
Root Cause Diagnosis PyAutoGUI raises FailSafeException when pyautogui.position() returns (0, 0) at the start of any API call (FAILSAFE = True, default FAILSAFE_POINTS = [(0, 0)]). Virtual and disconnected sessions report that value in two ways. On Xvfb, Xvnc and xrdp, no input device has moved the pointer, so it sits at the origin. On … Read more
Root Cause Diagnosis This error means ChromeDriver successfully launched the Chrome binary, but Chrome crashed or exited before it could open the DevTools debugging port that ChromeDriver polls to confirm a session started. ChromeDriver doesn’t report why Chrome died — it only knows the expected port file (DevToolsActivePort) inside the user-data directory never got written. … Read more
Root Cause Diagnosis This error occurs when Chromium’s headless rendering engine negotiates an HTTP/2 connection but fails mid-stream due to a mismatch between the container/VPS network stack and the server’s HTTP/2 flow-control expectations — most commonly triggered by missing or incompatible system libraries (libnss3, libgbm1) on minimal Linux distributions, or by a network layer (Docker bridge, … Read more