Akash Deep

Python script crashing with Segmentation Fault (core dumped) inside Docker Alpine

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A Python process crashing with Segmentation fault (core dumped) inside an Alpine Linux Docker container is primarily caused by C-extension memory allocation incompatibilities between Alpine’s musl libc implementation and glibc-compiled C extensions or binaries. Python packages containing pre-compiled C/C++ wheels (such as numpy, grpcio, pillow, pandas, or cryptography libraries) are typically linked against glibc using … Read more

Playwright async wait_for_selector timing out on dynamic Shadow DOM elements

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Playwright’s async wait_for_selector times out on dynamic Shadow DOM elements when target nodes reside inside closed shadow roots, are injected asynchronously via microtasks, or are queried using explicit XPath or pierce-incompatible CSS syntax. While Playwright’s default CSS engine automatically pierces open shadow roots, selectors that rely on traditional CSS strictness or improper piercing combinators break … Read more

Cloudflare Turnstile infinite loop on automated Chromium instance: Headless bypass flags

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Cloudflare Turnstile fails to issue a pass token and enters an infinite reloading loop on automated Chromium instances because it evaluates browser environment integrity at both the client runtime and network layers. Standard Chrome flags or unpatched headless modes expose active automation signals—such as the navigator.webdriver DOM attribute, anomalous WebGL/Canvas rendering strings, missing MediaDevices/AudioContext objects, … Read more

Fixing Selenium target window already closed error during fast alert handling

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The Selenium NoSuchWindowException: Message: target window already closed error during fast alert handling occurs when an automation script interacts with an alert (accepting, dismissing, or reading text) after the underlying browser window or frame that raised the alert has already been implicitly closed or detached. Race conditions emerge when script execution outpaces browser rendering engines, … Read more

Resolving Python multiprocessing deadlock with SQLite3 database locks

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A Python multiprocessing deadlock with SQLite3 occurs when multiple worker processes attempt concurrent writes to a single SQLite database file using standard connection objects. SQLite uses file-level or page-level locks (depending on the journaling mode) that block concurrent write access, while Python’s multiprocessing spawn/fork semantics can clone locked database connections or lock-waiting states across process … Read more

Step-by-step procedure to report credit card unauthorized tokenized recurring subscription

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Unauthorized tokenized recurring subscriptions occur when a merchant retains an active Payment Account Reference (PAR) or Network Token (e.g., Visa VTS, Mastercard MDES) and continues executing recurring Card-Not-Present (CNP) billing instructions through an automated standing instruction (SI) framework without explicit end-user consent. Network tokenization maps the customer’s actual Primary Account Number (PAN) to a surrogate … Read more

Resolving duplicate debit on POS terminal with transaction failed paper slip

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A duplicate debit accompanied by a “Transaction Failed” paper slip on a Point of Sale (POS) terminal occurs when the cardholder’s issuing bank processes an account authorization and debit instruction, but the POS terminal’s host handshake times out before receiving the final ISO 8583 response packet. The terminal’s terminal line controller drops the connection, prints … Read more

How to retrieve ARN (Acquirer Reference Number) for tracking lost international card refunds

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An Acquirer Reference Number (ARN) is a unique 23-digit identifier generated by the merchant’s acquiring bank when an international credit or debit card refund is routed through payment card networks (Visa, Mastercard, or American Express). When an international refund fails to reflect in the cardholder’s issuing bank account, it is typically because the cross-border settlement … Read more

UPI transaction status showing Success at sender bank but Not Credited to merchant

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A UPI transaction status showing Success at the remitter (sender) bank but failing to credit the beneficiary (merchant) account occurs due to an asynchronous decoupling between the debit leg and the credit leg within the Unified Payments Interface switch architecture. The Remitter Bank PSP successfully executes the debit instruction and transmits an ISO 20022/UPI payload … Read more

How to remove incorrect CIBIL overdue record caused by unreversed annual card fee

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An incorrect CIBIL overdue record caused by an unreversed annual credit card fee occurs when a card issuer levies a recurring fee on an inactive or zero-balance account without proper notice or despite a fee waiver agreement. Because the cardholder is unaware of the charge, the payment deadline passes, triggering a 30+ day past-due reporting … Read more