hyperledger/fabric · error

invalid mod_policy for element %s

Error message

invalid mod_policy for element %s

What it means

When processing each delta entry, its mod_policy is validated via validateModPolicy. This wrapped error means one of the changed elements has a missing or malformed mod_policy; see errors 144/145 for the inner causes.

Source

Thrown at common/configtx/update.go:76

	for i, pathElement := range strings.Split(trimmed, pathSeparator) {
		err := validateConfigID(pathElement)
		if err != nil {
			return errors.Wrapf(err, "path element at %d is invalid", i)
		}
	}
	return nil
}

func (vi *ValidatorImpl) verifyDeltaSet(deltaSet map[string]comparable, signedData []*protoutil.SignedData) error {
	if len(deltaSet) == 0 {
		return errors.Errorf("delta set was empty -- update would have no effect")
	}

	for key, value := range deltaSet {
		logger.Debugf("Processing change to key: %s", key)
		if err := validateModPolicy(value.modPolicy()); err != nil {
			return errors.Wrapf(err, "invalid mod_policy for element %s", key)
		}

		existing, ok := vi.configMap[key]
		if !ok {
			if value.version() != 0 {
				return errors.Errorf("attempted to set key %s to version %d, but key does not exist", key, value.version())
			}

			continue
		}
		if value.version() != existing.version()+1 {
			return errors.Errorf("attempt to set key %s to version %d, but key is at version %d", key, value.version(), existing.version())
		}

		policy, ok := vi.policyForItem(existing)
		if !ok {
			return errors.Errorf("unexpected missing policy %s for item %s", existing.modPolicy(), key)
		}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Set a valid ModPolicy (e.g. 'Admins') on every modified element in the write set.
2. Fix path syntax issues (empty segments, invalid characters) in the mod_policy.
3. Validate the delta set with validateModPolicy-equivalent checks client-side before submission.

Example fix

// before
delta["/Channel/Application/Org4"] = comparable{ConfigGroup: &cb.ConfigGroup{}} // no ModPolicy
// after
delta["/Channel/Application/Org4"] = comparable{ConfigGroup: &cb.ConfigGroup{ModPolicy: "Admins"}}

for key, value := range deltaSet {
  if err := validateModPolicy(value.modPolicy()); err != nil {
    return fmt.Errorf("element %s: %w", key, err)
  }
}

func deltaModPolicyOK(value comparable) bool { return validateModPolicy(value.modPolicy()) == nil }

err := validator.ProposeUpdate(env)
if err != nil && strings.Contains(err.Error(), "invalid mod_policy for element") {
  var key string
  fmt.Sscanf(err.Error(), "invalid mod_policy for element %s", &key)
  return fmt.Errorf("repair ModPolicy on %s and resubmit", key)
}

When it happens

Trigger: Submitting a ConfigUpdate whose delta set contains an element with an empty or syntactically invalid mod_policy string.

Common situations: Hand-crafted delta sets missing ModPolicy; SDK versions or tooling that don't populate ModPolicy on modified elements.

Related errors

• mod_policy not set
• path element at %d is invalid
• Attempted to set the batch size max message count to an inva
• Attempted to set the batch size absolute max bytes to an inv
• Attempted to set the batch size preferred max bytes to an in

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/744bbeae4b53b2a2. Report an issue: GitHub.