HV009ERRORTier 2 — Caution✅ HIGH confidence

FDW invalid use of null pointer

Category: Foreign Data Wrapper ErrorVersions: All Postgres versions (with FDW extension)

What this means

SQLSTATE HV009 is raised when a foreign data wrapper implementation uses a NULL pointer internally in an invalid context — this is typically a bug in the FDW extension code.

Why it happens

1A bug in a custom FDW C extension that dereferences a NULL pointer
2An FDW API callback receives an unexpected NULL value

How to reproduce

Buggy FDW extension dereferencing NULL.

trigger — this will ERROR

ERROR: FDW: invalid use of NULL pointer

Fix 1: Update the FDW extension to a patched version

When a third-party FDW is raising HV009.

fix

Why this works

HV009 typically indicates a bug in the FDW code. Check the FDW project issue tracker for known bugs, and upgrade to the latest version or apply a patch.

Fix 2: Add NULL checks in the FDW callback functions

When developing a custom FDW.

fix

Why this works

In C FDW implementations, validate all pointers received in FDW callback functions (fdw_routines) before dereferencing them.

Sources

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

🔧 Source ref: Class HV — Foreign Data Wrapper Error

Confidence assessment

✅ HIGH confidence

Standard SQLSTATE for FDW NULL pointer bugs. Stable across versions.