PostgreSQLERRORNotableExternal Routine Invocation ExceptionHIGH confidence

null value not allowed

Q: How to fix PostgreSQL 39004 null value not allowed?

Filter NULLs before calling STRICT functions: STRICT functions short-circuit on NULL inputs by convention, but filtering NULLs in SQL prevents the issue entirely.

What this means

SQLSTATE 39004 is raised when an external routine declared STRICT returns NULL in a context where NULL is not allowed, or passes NULL to a STRICT function argument.

Why it happens

1An external function declared STRICT is called with a NULL argument (STRICT functions return NULL for any NULL argument without executing — 39004 is raised if this contract is violated)

How to reproduce

STRICT external function receiving a NULL argument explicitly.

expected output

ERROR:  null value not allowed

Fix

Filter NULLs before calling STRICT functions

WHEN When calling STRICT external functions with nullable data.

Filter NULLs before calling STRICT functions

SELECT my_strict_fn(col) FROM data WHERE col IS NOT NULL;

Why this works

STRICT functions short-circuit on NULL inputs by convention, but filtering NULLs in SQL prevents the issue entirely.

Sources

Official documentation ↗

Class 39 — External Routine Invocation Exception

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At a glance

PlatformPostgreSQL SQLSTATE Errors

Code39004

ClassExternal Routine Invocation Exception

SeverityERROR

TierNotable

ConfidenceHIGH