What steps should I take if I encounter an 'ODBC error HY000' related to a specific query that was previously working?

If a previously working query now fails with HY000, consider recent changes. Has the database schema been altered? Have there been any updates to the database server, the ODBC driver, or the application connecting to it? Review database logs for more specific error messages that might accompany the HY000 code. Temporarily simplifying the query to isolate the problematic part can also be helpful.