string_data_right_truncation value too long for type character varying(N) — 22001

Symptoms

A string is longer than the declared length of a varchar(n)/char(n) column. PostgreSQL refuses to truncate silently and raises SQLSTATE 22001 (string_data_right_truncation).

• The message includes the maximum length (n).
• Common after a UI accepts longer input than the column allows.
• Affects INSERT, UPDATE, and casts to a length-limited type.

What the server log shows

ERROR:  value too long for type character varying(20)

Why PostgreSQL raises this — what the manual says

Section 8.3 Character Types:

“However, if one explicitly casts a value to character varying(n) or character(n), then an over-length value will be truncated to n characters without raising an error.”

A length-qualified character type enforces its maximum on assignment. A value exceeding n (with non-space overflow) cannot be stored without data loss, so PostgreSQL aborts with 22001 rather than truncating.

Common causes

• Input longer than the column’s declared length.
• An under-sized column relative to real data.
• Concatenation producing a longer string than expected.

How to fix it

1. Widen the column: ALTER TABLE t ALTER COLUMN name TYPE varchar(255); (or use text).
2. Validate/limit input length in the application.
3. Deliberately truncate when acceptable: left(value, 20).

Related & next steps

• SQLSTATE 22001 — String Data Right Truncation (full reference)
• Message: invalid input syntax for type numeric
• Glossary: Character type

Reference: PostgreSQL 18 Section 8.3 “Character Types”.