What causes "invalid timeTruncate value: %v, error: %w" in go-sql-driver/mysql?

Use a valid Go duration such as '1s', '500ms', or '1m'.

invalid timeTruncate value

Error message

invalid timeTruncate value: %v, error: %w

What it means

The 'timeTruncate' DSN parameter is parsed with time.ParseDuration and controls truncation of scanned time values to the given granularity (e.g. "1s" drops sub-second precision). This error wraps the ParseDuration failure when the value is not a valid Go duration string.

Solutions

Use a valid Go duration such as '1s', '500ms', or '1m'.
Remove the timeTruncate parameter entirely if you do not need time truncation.
Confirm the value against time.ParseDuration rules (number + optional fraction + unit: ns/us/ms/s/m/h).

Example fix

// before
sql.Open("mysql", "user@tcp(127.0.0.1:3306)/db?parseTime=true&timeTruncate=second")
// after
sql.Open("mysql", "user@tcp(127.0.0.1:3306)/db?parseTime=true&timeTruncate=1s")

Defensive patterns

Strategy: validation

Validate before calling

// Validate the duration string before building the DSN.
import "time"
if _, err := time.ParseDuration(timeTruncateVal); err != nil {
    return fmt.Errorf("timeTruncate must be a duration: %w", err)
}

Type guard

null

Try / catch

// ParseDSN/DSN-Format errors are returned from ParseDSN; check the error.
if _, err := mysql.ParseDSN(dsn); err != nil {
    return err
}

Prevention

Remember timeTruncate takes a Go duration (e.g. 1s), not a word.
Reuse time.ParseDuration in a unit test for any DSN you assemble.
Omit timeTruncate unless you specifically need sub-second truncation.

When it happens

Trigger: A DSN containing '?timeTruncate=...' with a value time.ParseDuration rejects, e.g. 'timeTruncate=second', 'timeTruncate=', or 'timeTruncate=1.5' (no unit).

Common situations: Confusing the parameter for a human-readable word like 'seconds' or 'minute'; passing a numeric without a unit; copy-paste from documentation that omits the unit.

Related errors

AI-assisted analysis of go-sql-driver/mysql@03d76c7e07 (2026-08-07). Data as JSON: /api/errors/fe1a917941960cc0. Report an issue: GitHub.

Appendix: source

Thrown at dsn.go:610

			var isBool bool
			cfg.MultiStatements, isBool = readBool(value)
			if !isBool {
				return errors.New("invalid bool value: " + value)
			}

		// time.Time parsing
		case "parseTime":
			var isBool bool
			cfg.ParseTime, isBool = readBool(value)
			if !isBool {
				return errors.New("invalid bool value: " + value)
			}

		// time.Time truncation
		case "timeTruncate":
			cfg.timeTruncate, err = time.ParseDuration(value)
			if err != nil {
				return fmt.Errorf("invalid timeTruncate value: %v, error: %w", value, err)
			}

		// I/O read Timeout
		case "readTimeout":
			cfg.ReadTimeout, err = time.ParseDuration(value)
			if err != nil {
				return
			}

		// Reject read-only connections
		case "rejectReadOnly":
			var isBool bool
			cfg.RejectReadOnly, isBool = readBool(value)
			if !isBool {
				return errors.New("invalid bool value: " + value)
			}

		// Server public key

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