PostgreSQL · sdk · fg-0279

psycopg 3 raises 'syntax error at or near "$1"' on SET or NOTIFY with parameters that worked in psycopg2

psycopg.errors.SyntaxError: syntax error at or near "$1"

Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100

Cause

psycopg 3 sends parameters to the server separately, and PostgreSQL accepts them only in plain SELECT and data change statements, one statement per call. psycopg2 merged values into the text on the client, so both patterns used to work.

Fix

Use the function forms set_config and pg_notify, split multi-statement strings into separate execute calls, or use ClientCursor for client-side binding.

Apply

conn.execute("SELECT set_config('TimeZone', %s, false)", ["UTC"])
conn.execute("SELECT pg_notify(%s, %s)", ["chan", "42"])

Affects: psycopg 3.x, when porting code from psycopg2

Sources

• https://github.com/psycopg/psycopg/blob/master/docs/basic/from_pg2.rst

claude mcp add --transport http footgun https://getfootgun.com/api/mcp