What causes "config ID illegal, cannot be longer than %d" in hyperledger/fabric?

Shorten the config ID to at most MaxLength (250) characters

config ID illegal, cannot be longer than %d

Error message

config ID illegal, cannot be longer than %d

What it means

validateConfigID enforces a maximum identifier length (MaxLength, 250 characters). Config IDs longer than this limit are rejected to keep configuration paths bounded. The error includes the numeric limit.

Source

Thrown at common/configtx/validator.go:55

	configMap   map[string]comparable
	configProto *cb.Config
	namespace   string
	pm          policies.Manager
}

// validateConfigID makes sure that the config element names (ie map key of
// ConfigGroup) comply with the following restrictions
//  1. Contain only ASCII alphanumerics, dots '.', dashes '-'
//  2. Are shorter than 250 characters.
//  3. Are not the strings "." or "..".
func validateConfigID(configID string) error {
	re, _ := regexp.Compile(configAllowedChars)
	// Length
	if len(configID) <= 0 {
		return errors.New("config ID illegal, cannot be empty")
	}
	if len(configID) > MaxLength {
		return errors.Errorf("config ID illegal, cannot be longer than %d", MaxLength)
	}
	// Illegal name
	if _, ok := illegalNames[configID]; ok {
		return errors.Errorf("name '%s' for config ID is not allowed", configID)
	}
	// Illegal characters
	matched := re.FindString(configID)
	if len(matched) != len(configID) {
		return errors.Errorf("config ID '%s' contains illegal characters", configID)
	}

	return nil
}

// ValidateChannelID makes sure that proposed channel IDs comply with the
// following restrictions:
//  1. Contain only lower case ASCII alphanumerics, dots '.', and dashes '-'
//  2. Are shorter than 250 characters.

View on GitHub (pinned to 2736b63f8f)

Solutions

Shorten the config ID to at most MaxLength (250) characters
Use an abbreviated or hashed identifier and map it to the long name elsewhere
Add a length check in any tooling that generates config keys
Split deeply nested names into config group hierarchy instead of one long flat ID

Example fix

// before
id := orgName + "." + region + "." + serviceName // may exceed 250 chars
if len(id) > 250 {
    return errors.New("config ID too long")
}
// after
id := abbreviate(orgName) + "." + region + "." + serviceName // <= 250 chars

Defensive patterns

Strategy: validation

Validate before calling

const maxLen = 250
if len(configID) > maxLen {
    return errors.Errorf("config ID %d chars exceeds max %d", len(configID), maxLen)
}

Type guard

func validConfigIDLength(id string) bool {
    return len(id) <= 250
}

Try / catch

if err := configtx.ValidateChannelID(id); err != nil {
    return fmt.Errorf("config ID rejected: %w", err)
}

Prevention

Cap name lengths in generators that compose IDs from multiple parts
Use hashes/abbreviations for very long names
Assert on generated config key lengths in CI
Prefer hierarchy (nested groups) over long flat IDs

When it happens

Trigger: Using extremely long organization names, MSP or policy names as config IDs; programmatically concatenating names into keys exceeding 250 chars.

Common situations: Auto-generated config keys built from FQDNs or long org paths; copying long service names into config element IDs; nested group names assembled without length checks.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/01d307b6f0571ebb. Report an issue: GitHub.