windowing_error window “…” does not exist — 42P20

Symptoms

An OVER windowname referenced a named window that was not defined in the query’s WINDOW clause. PostgreSQL raises SQLSTATE 42P20 (windowing_error).

• A window name in OVER has no matching WINDOW definition.
• Typo or missing WINDOW clause entry.
• Named windows must be declared before use.

What the server log shows

ERROR:  window "w" does not exist

Why PostgreSQL raises this — what the manual says

As Section 4.2.8 Window Function Calls explains:

An OVER windowname clause referenced a named window that was never defined in the query’s WINDOW clause; define the window in WINDOW, or write the window specification inline within the OVER (…) parentheses.

When OVER windowname is used, PostgreSQL looks the name up in the query’s WINDOW clause. If no matching definition exists, the reference cannot be resolved and it reports 42P20.

Common causes

• A typo in the window name.
• Missing the corresponding WINDOW name AS (…) definition.
• Referencing a window defined in a different query level.

How to fix it

1. Define the window: … WINDOW w AS (PARTITION BY x ORDER BY y).
2. Match the name exactly between OVER and the WINDOW clause.
3. Inline the window definition in OVER if you don’t need a named window.

Related & next steps

• SQLSTATE 42P20 — Windowing Error (full reference)
• Message: window function requires an OVER clause
• Glossary: Window function

Reference: PostgreSQL 18 Section 4.2 “Value Expressions”.