x_code Summary This incident examines why a seemingly simple request—plotting a weighted average of two ETF percent‑change series in TradingView Supercharts—fails when implemented naively. Although the user expected Pine Script to directly combine percent‑scaled overlays, the underlying data model of TradingView makes this non‑trivial. The postmortem breaks down what went wrong, why it happens, and how … Read more
Summary This incident analyzes why rm -rf on PolarDB-FileSystem (FUSE mode) is dramatically slower than the same operation on ext4, despite running on the same NVMe SSD. The core issue stems from metadata-heavy operations crossing the user–kernel boundary, compounded by FUSE design constraints and PolarDB-FileSystem’s metadata architecture. Root Cause The slowdown is caused by a … Read more
Summary Choosing the right back-end for a React web app can be daunting, especially for beginners. Key factors include ease of learning, integration with AI/ML, and scalability. For a B.Tech CSE (AIML) student proficient in Python, Flask or FastAPI are ideal choices due to their simplicity, Python-based ecosystem, and compatibility with AI/ML libraries. Root Cause … Read more
Summary The expo-location API failed to retrieve location data on physical Android devices, despite functioning correctly on iOS devices and Android emulators. The issue stemmed from inconsistent permission handling and background service limitations on Android. Root Cause Permission Granting Discrepancy: Android devices required explicit runtime permissions, which were not consistently granted or handled. Background Service … Read more
Summary The issue involves an AXS15231B LCD (model JC3248W535EN) connected via QSPI on an ESP32-S3 using ESP-IDF v5.5.2. The backlight functions correctly, but the display remains blank despite successful initialization and no error logs. The root cause lies in incorrect QSPI bus configuration and missing panel initialization commands. Root Cause Incorrect QSPI bus configuration: The … Read more
Summary The teleport line in a Unity VR project using the XR Toolkit is hidden by a transparent material placed in front of the camera, even when the material’s alpha is set to 0. The issue occurs due to render queue conflicts and depth testing, causing the teleport line to be incorrectly occluded. Root Cause … Read more
Summary The issue arises when a dynamically added node attempts to reference another node using @onready and node paths ($car). The referenced node (car) is not found because the dynamic node’s script is initialized before the scene tree is fully constructed, leading to null references. Root Cause Dynamic node addition: The Sprite2D node with PropPassthrough … Read more
Summary The issue arises when using GNU Make’s pattern rules with directory structures. The stem ($*) in a pattern rule like deps/%.d is expanded based on the target’s basename, not its full path. This leads to unexpected directory prefixes when the target is in a subdirectory. Root Cause Pattern Rule Expansion: GNU Make’s pattern rules … Read more
Summary Cross-compiling for ARM64 using Visual Studio 2022 and WSL2 resulted in x64 binaries instead of the expected ARM64 output. Despite correct configurations and toolchains, the build system defaulted to the host architecture, ignoring the target platform. Root Cause The root cause was Visual Studio’s default behavior of using the host toolchain (x64) instead of … Read more
Summary This postmortem analyzes a wkhtmltopdf table‑rendering defect where repeated table headers overlap content when a single table row spans multiple pages. Although the HTML renders correctly in browsers, wkhtmltopdf’s legacy layout engine fails to reserve vertical space for the repeated header, causing visual corruption and truncated content. Root Cause The underlying issue is a … Read more