fatedier/frp · error

unit not support

Error message

unit not support

What it means

BandwidthQuantity.UnmarshalJSON (pkg/config/types/types.go:80) accepts only strings suffixed with KB or MB (e.g. "1MB", "512KB"); any other unit — or a bare number string — hits the else branch and returns 'unit not support'. Bandwidth values in frp configs are parsed through this type (bandwidthLimit fields).

Source

Thrown at pkg/config/types/types.go:80

func (q *BandwidthQuantity) UnmarshalString(s string) error {
	s = strings.TrimSpace(s)
	if s == "" {
		return nil
	}

	var (
		base int64
		f    float64
		err  error
	)
	if fstr, ok := strings.CutSuffix(s, "MB"); ok {
		base = MB
		f, err = strconv.ParseFloat(fstr, 64)
	} else if fstr, ok := strings.CutSuffix(s, "KB"); ok {
		base = KB
		f, err = strconv.ParseFloat(fstr, 64)
	} else {
		return errors.New("unit not support")
	}
	if err != nil {
		return err
	}

	q.s = s
	q.i = int64(f * float64(base))
	return nil
}

func (q *BandwidthQuantity) UnmarshalJSON(b []byte) error {
	if len(b) == 4 && string(b) == "null" {
		return nil
	}

	var str string
	err := json.Unmarshal(b, &str)
	if err != nil {

View on GitHub (pinned to 6c8a8d0a97)

Solutions

1. Express the limit in KB or MB, e.g. "1024KB" or "1MB" (convert 1GB to "1024MB")
2. Remove bandwidthLimit when no limit is intended
3. Fix casing: suffix must be exactly 'KB' or 'MB'
4. Validate bandwidth strings with a ^\d+(\.\d+)?(KB|MB)$ check in your config pipeline

Example fix

# before
transport.bandwidthLimit = "100MBps"
# or
proxies[0].transport.bandwidthLimit = "1GB"

# after
transport.bandwidthLimit = "100MB"
proxies[0].transport.bandwidthLimit = "1024MB"

var bandwidthRe = regexp.MustCompile(`^\d+(\.\d+)?(KB|MB)$`)

if !bandwidthRe.MatchString(cfg.Transport.BandwidthLimit) {
    return fmt.Errorf("bandwidthLimit %q must end in KB or MB", cfg.Transport.BandwidthLimit)
}

if err := json.Unmarshal(data, &cfg); err != nil {
    if strings.Contains(err.Error(), "unit not support") {
        return fmt.Errorf("bandwidth values must be like \"1MB\" or \"512KB\" (GB/Mbps/bare numbers unsupported)")
    }
    return err
}

When it happens

Trigger: Setting bandwidthLimit = "1GB", bandwidthLimit = "100", bandwidthLimit = "10mbps", or any value whose suffix is not exactly KB/MB (case-sensitive per CutSuffix), then starting frpc/frps or reloading — config decode fails at that field.

Common situations: Assuming GB or Mbps are accepted because other tools use them; pasting bandwidth numbers without units; casing differences like 'Mb'; upgrading from configs that were never validated strictly.

Related errors

• ErrHealthCheckType
• type is required
• failed to parse JSON: %w
• proxy [%s] is repeated
• xtcp server for [%s] doesn't exist

AI-assisted analysis of fatedier/frp@6c8a8d0a97 (2026-08-15). Data as JSON: /api/errors/78e3b09ae567f64c. Report an issue: GitHub.