string data length mismatch

Category: Data ExceptionVersions: All Postgres versions

What this means

SQLSTATE 22026 is raised when a string value has a length that does not match the expected or declared length — for example, when a CHAR(n) value being compared or converted has a different byte length than required.

Why it happens

1A string value does not match the required fixed length in a context that mandates exact length
2Multi-byte encoding means a character string has more bytes than characters, conflicting with a byte-length check

How to reproduce

String length mismatch in a fixed-length context.

trigger — this will ERROR

ERROR: string data length mismatch

Fix 1: Ensure string values match the required length or use variable-length types

When working with CHAR(n) columns or fixed-length string operations.

fix

-- Use VARCHAR(n) instead of CHAR(n) to avoid length padding issues:
ALTER TABLE codes ALTER COLUMN code TYPE VARCHAR(10);

Why this works

VARCHAR is more flexible than CHAR for variable-length content. CHAR pads with spaces to the fixed length, which can cause comparison issues.

Sources

📚 Official docs: https://www.postgresql.org/docs/current/errcodes-appendix.html

🔧 Source ref: Class 22 — Data Exception

Confidence assessment

✅ HIGH confidence

Standard SQLSTATE. Stable across versions.