One digit broke the QR: why successful reading is not enough

In this Habr article, the author analyzes a problem where visually correct QR codes can contain hidden errors that prevent successful decoding. The study focuses on the technical aspects of data encoding, comparing two QR codes of the same size where a single incorrect digit causes decoder failure. The material details the data's path through the encoder, compares 160 combinations of versions and error correction levels, and performs 960 tests using the Nayuki library. The author demonstrates that a simple successful scan is not enough to guarantee the correctness of a QR code, as errors can be buried within the data structure. The article includes illustrations and code for running your own experiments, making it a valuable resource for developers working with QR code generation and validation.