jackc/pgx · error

invalid element count %d at offset %d

Error message

invalid element count %d at offset %d

What it means

Error "invalid element count %d at offset %d" thrown in jackc/pgx.

Source

Thrown at internal/pgio/read.go:162

	}
	b := r.s[r.rp : r.rp+i]
	r.rp += i + 1
	return b
}

// Count reads an int32 element count and validates it against the remaining
// bytes: the count must be non-negative, and since each element occupies at
// least minElemSize bytes, count*minElemSize must not exceed the remaining
// message. This bounds allocations sized from the count against a malicious
// or corrupt message claiming a huge count. Returns 0 on any failure.
func (r *Reader) Count(minElemSize int) int {
	offset := r.rp
	count := int(r.Int32())
	if r.err != nil {
		return 0
	}
	if count < 0 {
		r.fail(fmt.Errorf("invalid element count %d at offset %d", count, offset))
		return 0
	}
	if minElemSize < 1 {
		minElemSize = 1
	}
	if count > r.Remaining()/minElemSize {
		r.fail(fmt.Errorf("element count %d at offset %d exceeds %d remaining bytes", count, offset, r.Remaining()))
		return 0
	}
	return count
}

// Value reads an int32 length followed by that many bytes — the standard
// PostgreSQL binary representation of a value. A length of -1 means NULL and
// returns (nil, true). Any other negative length is an error. The returned
// slice aliases the source; null is only meaningful if Err returns nil.
func (r *Reader) Value() (data []byte, null bool) {
	offset := r.rp

View on GitHub (pinned to ec1a0befd2)

When it happens

Trigger: Thrown at internal/pgio/read.go:162 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: /data/errors/1540d329beed8e6e.json. Report an issue: GitHub.