Programming Tutorials

  In data engineering, few things are as frustrating as a pipeline failure caused by a single malformed character in a 5GB XML feed. If you rely on Python’s built-in  xml.etree.ElementTree , you likely encounter the dreaded  ParseError: not well-formed (invalid token) . Standard XML parsers are designed to fail fast. According to the W3C specification, if XML is not strictly "well-formed," it is fatal. However, the real world is messy. Legacy systems produce unescaped ampersands, web scrapers retrieve truncated responses, and third-party APIs often deliver "XML-ish" data that breaks strict validators. Halting execution is rarely an option. This guide details how to implement robust, fault-tolerant XML parsing using Python and  lxml . The Root Cause: Why Standard Parsers Fail To fix the problem, we must understand the mechanics of the failure. Python's standard library  xml.etree.ElementTree  is often backed by the Expat parser. Expat is a stream-oriented pa...