hyperledger/fabric · error

error computing config update

Error message

error computing config update

What it means

update.Compute(origConf, updtConf) computes the delta between the two channel configs and failed; wrapped as "error computing config update". Compute returns errors when the two configs are structurally incompatible for diffing — most notably different channel IDs, or invalid/missing groups and policies.

Source

Thrown at cmd/configtxlator/main.go:218

	err = proto.Unmarshal(origIn, origConf)
	if err != nil {
		return errors.Wrapf(err, "error unmarshalling original config")
	}

	updtIn, err := io.ReadAll(updated)
	if err != nil {
		return errors.Wrapf(err, "error reading updated config")
	}

	updtConf := &cb.Config{}
	err = proto.Unmarshal(updtIn, updtConf)
	if err != nil {
		return errors.Wrapf(err, "error unmarshalling updated config")
	}

	cu, err := update.Compute(origConf, updtConf)
	if err != nil {
		return errors.Wrapf(err, "error computing config update")
	}

	cu.ChannelId = channelID

	outBytes, err := proto.Marshal(cu)
	if err != nil {
		return errors.Wrapf(err, "error marshaling computed config update")
	}

	_, err = output.Write(outBytes)
	if err != nil {
		return errors.Wrapf(err, "error writing config update to output")
	}

	return nil
}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Verify both configs are for the same channel ID (compare the channel_id in decoded JSON)
2. Regenerate the updated config from the actual current config of the target channel
3. Undo invalid manual edits (e.g. removed required groups/policies) and re-diff
4. Pull a fresh config from the ordering service and redo decode → edit → encode → compute-update

Example fix

// before
configtxlator compute-update --channel channelA --original channelB_config.pb --updated updt.pb ...
// after
configtxlator compute-update --channel channelA --original channelA_current.pb --updated channelA_edited.pb ...

// decode both and compare channel IDs before compute-update
grep -o '"channel_id":"[^"]*"' config.json updated.json | sort -u | wc -l | grep -q '^1$' || { echo "channel mismatch"; exit 1; }

out, err := cmd.CombinedOutput()
if err != nil && strings.Contains(string(out), "error computing config update") {
    // refetch current config from orderer and rebuild the diff
}

When it happens

Trigger: Original and updated configs belong to different channels, a config group was removed entirely where removal is unsupported, policy references are broken, or the configs are empty/invalid after unmarshal.

Common situations: Comparing configs from different channels by mistake, building the updated config on a mismatched base (out-of-sync orderer state), or hand-editing JSON so group/version structure became invalid.

Related errors

• error reading input
• error unmarshalling
• error encoding output
• error reading original config
• error unmarshalling original config

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/bd6ac4e90cd8884b. Report an issue: GitHub.