syntax_error syntax error at end of input — 42601

Symptoms

The parser reached the end of the statement while still expecting more tokens — the SQL is incomplete. PostgreSQL raises SQLSTATE 42601 (syntax_error).

• The statement was cut off before it was complete.
• Common with a trailing operator, open parenthesis, or missing clause.
• The error points at the end of the input.

What the server log shows

ERROR:  syntax error at end of input
LINE 1: SELECT * FROM orders WHERE id =
                                       ^

Why PostgreSQL raises this — what the manual says

Section 4.1 Lexical Structure:

“A command is composed of a sequence of tokens, terminated by a semicolon”

The parser expects a grammatically complete statement. When the input ends while a clause/expression is still unfinished, it cannot complete the parse and reports 42601 at end of input.

Common causes

• A dangling operator or comparison with no right-hand side.
• An unclosed parenthesis or quote truncating the statement.
• String concatenation in code that dropped the tail of the query.

How to fix it

1. Complete the statement (supply the missing expression/clause).
2. Balance parentheses and quotes.
3. Log the full generated SQL to spot where it was truncated.

Related & next steps

• SQLSTATE 42601 — Syntax Error (full reference)
• Message: each UNION query must have the same number of columns
• Glossary: Parser

Reference: PostgreSQL 18 Section 4.1 “Lexical Structure”.