jackc/pgx · error

hstore pair : key cannot be NULL

Error message

hstore pair %d: key cannot be NULL

What it means

Binary hstore decoding guard: pair %d's key bytes were marked NULL by the length header. PostgreSQL's hstore never allows NULL keys, so this indicates a corrupt or maliciously crafted binary payload, not valid hstore data.

Solutions

1. Treat as corrupted or maliciously crafted data
2. Verify the hstore extension produced the value

When it happens

Trigger: Thrown at pgtype/hstore.go:208 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of jackc/pgx@ec1a0befd2 (2026-08-04). Data as JSON: /api/errors/ed3387da8ff2364d. Report an issue: GitHub.

Appendix: source

Thrown at pgtype/hstore.go:208

	// Each pair carries at minimum two int32 length headers (key, value). This bounds the
	// up-front make() against a malicious server claiming a huge pair count in a small message.
	pairCount := r.Count(8)
	if err := r.Err(); err != nil {
		return fmt.Errorf("hstore: %w", err)
	}

	hstore := make(Hstore, pairCount)
	// one allocation for all *string, rather than one per string, just like text parsing
	valueStrings := make([]string, pairCount)

	for i := range pairCount {
		keyBytes, keyNull := r.Value()
		valueBytes, valueNull := r.Value()
		if err := r.Err(); err != nil {
			return fmt.Errorf("hstore pair %d: %w", i, err)
		}
		if keyNull {
			return fmt.Errorf("hstore pair %d: key cannot be NULL", i)
		}

		key := string(keyBytes)
		if valueNull {
			hstore[key] = nil
		} else {
			valueStrings[i] = string(valueBytes)
			hstore[key] = &valueStrings[i]
		}
	}

	if err := r.Finish(); err != nil {
		return fmt.Errorf("hstore: %w", err)
	}
	return scanner.ScanHstore(hstore)
}

type scanPlanTextAnyToHstoreScanner struct{}

View on GitHub (pinned to ec1a0befd2)