01P01WARNINGTier 2 — Caution✅ HIGH confidence

deprecated feature

Category: WarningVersions: All Postgres versions

What this means

SQLSTATE 01P01 is a Postgres-specific warning raised when a client uses a syntax, function, or feature that is deprecated and scheduled for removal in a future version. The statement still executes but may break on upgrade.

Why it happens

1Using deprecated SQL syntax or functions that Postgres has marked for removal
2Using removed GUC parameter names that have been renamed
3Relying on implicit casts or behaviours that Postgres is phasing out

How to reproduce

Using a deprecated function or syntax.

trigger — this will ERROR

-- Example: using deprecated timestamp without timezone implicit coercion
SET standard_conforming_strings = off; -- deprecated in some configurations

WARNING: nonstandard use of \\ in a string literal

Fix 1: Replace deprecated usage with the recommended alternative

When 01P01 warnings appear in logs, especially before a major version upgrade.

fix

Why this works

Read the Postgres release notes for the version where the deprecation was announced and apply the recommended migration path before upgrading.

What not to do

✗

Ignore 01P01 warnings before a major upgrade

Why it's wrong: Deprecated features are removed in subsequent major versions, causing failures after upgrade.

Version notes

All major versionsReview the Postgres release notes under "Deprecated Features" for each major version.

Sources

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

🔧 Source ref: Class 01 — Warning (Postgres-specific)

📖 Further reading: PostgreSQL Release Notes

Confidence assessment

✅ HIGH confidence

Postgres-specific extension to the SQL standard warning class. Widely used for deprecation notices across major versions.