Minimal reproducer seems to be this: ---------- import xml.etree.ElementTree as etree def test(): parser = etree.XMLParser() try: parser.close() except etree.ParseError as exc: e = exc # must keep local reference! test() ---------- The master gitrev I tested is 132a7d7cdbc7cb89fa1c1f4e8192241c3d68f549 Since this happens during GC and finalisation, it's quite possible that it's not a bug in ET per se. It might just be a prematurely cleared reference in some tp_clear(), or something like that. (Changing ticket title appropriately.)