Server closed the connection unexpectedly in Postgres

Now-Next's Chris van Eijk tested what PostgreSQL's "server closed the connection unexpectedly" message hides, using Docker images 13 to 18 and six client libraries. The sentence comes from libpq, not the server, and the server log is the main clue. In an autocommit loop with kill -9, 77 of 100 failed statements had in fact committed, so blind retries risk duplicates. pg_xact_status sometimes reported lost transactions as committed after a crash. Most figures are the author's own measurements and have no independent source.