undefined_parameter there is no parameter $N — 42P02

Symptoms

A query used a positional parameter placeholder ($n) for which no value was supplied. PostgreSQL raises SQLSTATE 42P02 (undefined_parameter).

• A $n placeholder has no bound value.
• Common when the parameter count doesn’t match the bound values.
• Often off-by-one in driver parameter arrays.

What the server log shows

ERROR:  there is no parameter $2
LINE 1: SELECT * FROM orders WHERE id = $1 AND status = $2;

Why PostgreSQL raises this — what the manual says

As Section 4.3 Calling Functions explains:

A function call used a named argument whose name the function does not declare; named arguments must match the function’s declared parameter names exactly, so check the function signature or switch to positional notation.

Prepared/parameterized statements bind values to $1, $2, …. If the statement references a parameter number for which no value was provided, PostgreSQL cannot resolve it and reports 42P02.

Common causes

• Fewer values bound than placeholders referenced.
• An off-by-one in the driver’s parameter array.
• Building SQL with a higher $n than parameters passed.

How to fix it

1. Bind a value for every $n the statement uses.
2. Ensure the parameter array length matches the highest placeholder.
3. Check driver-specific parameter numbering (1-based).

Related & next steps

• SQLSTATE 42P02 — Undefined Parameter (full reference)
• Message: missing FROM-clause entry for table
• Glossary: Prepared statement

Reference: PostgreSQL 18 Section 4 “SQL Syntax”.