benbjohnson/litestream · error

invalid size format: %w

Error message

invalid size format: %w

What it means

ParseByteSize failed because github.com/dustin/go-humanize could not interpret the string as a byte size. The underlying humanize error is chained, indicating unsupported units or non-numeric characters.

Source

Thrown at cmd/litestream/main.go:1100

		return err
	}
	*b = ByteSize(size)
	return nil
}

// ParseByteSize parses a byte size string using github.com/dustin/go-humanize.
// Supports both SI units (KB=1000, MB=1000², etc.) and IEC units (KiB=1024, MiB=1024², etc.).
// Examples: "1MB", "5MiB", "1.5GB", "100B", "1024KB"
func ParseByteSize(s string) (int64, error) {
	s = strings.TrimSpace(s)
	if s == "" {
		return 0, fmt.Errorf("empty size string")
	}

	// Use go-humanize to parse the byte size string
	bytes, err := humanize.ParseBytes(s)
	if err != nil {
		return 0, fmt.Errorf("invalid size format: %w", err)
	}

	// Check that the value fits in int64
	if bytes > math.MaxInt64 {
		return 0, fmt.Errorf("size %d exceeds maximum allowed value (%d)", bytes, int64(math.MaxInt64))
	}

	return int64(bytes), nil
}

// ReplicaSettings contains settings shared across replica configurations.
// These can be set globally in Config or per-replica in ReplicaConfig.
type ReplicaSettings struct {
	SyncInterval       *time.Duration `yaml:"sync-interval"`
	ValidationInterval *time.Duration `yaml:"validation-interval"`

	// Maximum L0 files to upload in a single monitor sync run.
	// Set to zero to process all pending L0 files in one run.

View on GitHub (pinned to 4ed7a308f6)

Solutions

1. Use supported forms: "1MB", "5MiB", "1.5GB", "100B", "1024KB"
2. Remove thousands separators and stray characters from the value
3. Check the chained humanize error text for the offending character

Example fix

# before
max-size: 1,5GB
# after
max-size: 1.5GB

if _, err := humanize.ParseBytes(cfg.Size); err != nil {
    return fmt.Errorf("size %q not parseable: use forms like 1MB, 5MiB, 1.5GB", cfg.Size)
}

When it happens

Trigger: Config size values like "1 gb" with unsupported spelling, "10 bytes" , "1,5GB", "abc", or trailing characters such as "5MB!" passed to a size config field.

Common situations: Typos in unit suffixes (e.g. "5mB" vs "5MB"), locale-formatted numbers with commas, users writing durations where sizes are expected.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• parse replica url: %w
• empty size string
• size %d exceeds maximum allowed value (%d)
• cannot parse exec command: %w
• heartbeat URL must be a valid HTTP or HTTPS URL

AI-assisted analysis of benbjohnson/litestream@4ed7a308f6 (2026-09-06). Data as JSON: /api/errors/13758e8f69c5de05. Report an issue: GitHub.