jackc/pgx · error

cannot get param

Error message

cannot get param %d: %w

What it means

While unmarshaling a JSON-encoded Bind message, a parameter value could not be decoded — the wrapped error comes from the per-parameter JSON value extraction. This is used by tooling that serializes protocol messages as JSON.

Solutions

1. Check the wrapped error for the JSON decoding detail
2. Verify parameter values are valid JSON objects with a recognized type key
3. Use base64 for binary parameter values
4. Inspect the JSON structure against Bind.UnmarshalJSON expectations

When it happens

Trigger: Thrown at pgproto3/bind.go:219 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/315142f2801c3a11. Report an issue: GitHub.

Appendix: source

Thrown at pgproto3/bind.go:219

		DestinationPortal    string
		PreparedStatement    string
		ParameterFormatCodes []int16
		Parameters           []map[string]string
		ResultFormatCodes    []int16
	}
	err := json.Unmarshal(data, &msg)
	if err != nil {
		return err
	}
	dst.DestinationPortal = msg.DestinationPortal
	dst.PreparedStatement = msg.PreparedStatement
	dst.ParameterFormatCodes = msg.ParameterFormatCodes
	dst.Parameters = make([][]byte, len(msg.Parameters))
	dst.ResultFormatCodes = msg.ResultFormatCodes
	for n, parameter := range msg.Parameters {
		dst.Parameters[n], err = getValueFromJSON(parameter)
		if err != nil {
			return fmt.Errorf("cannot get param %d: %w", n, err)
		}
	}
	return nil
}

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