hyperledger/fabric · error

failed to unmarshal output from 'go list'

Error message

failed to unmarshal output from 'go list'

What it means

listModuleInfo runs 'go list -m -json' in module mode and json.Unmarshals its output; if the output is not valid JSON matching the expected shape, it wraps the failure with 'failed to unmarshal output from 'go list''. Indicates the go tool produced unexpected output.

Source

Thrown at core/chaincode/platforms/golang/list.go:133

	cmd := exec.CommandContext(ctx, "go", "list", "-json", ".")
	cmd.Env = append(os.Environ(), extraEnv...)

	output, err := cmd.Output()
	if err != nil {
		return nil, wrapExitErr(err, "'go list' failed")
	}

	var moduleData struct {
		ImportPath string
		Module     struct {
			Dir   string
			Path  string
			GoMod string
		}
	}

	if err := json.Unmarshal(output, &moduleData); err != nil {
		return nil, errors.Wrap(err, "failed to unmarshal output from 'go list'")
	}

	return &ModuleInfo{
		Dir:        moduleData.Module.Dir,
		GoMod:      moduleData.Module.GoMod,
		ImportPath: moduleData.ImportPath,
		ModulePath: moduleData.Module.Path,
	}, nil
}

View on GitHub (pinned to 2736b63f8f)

Solutions

1. Check GOFLAGS and GOENV for settings that make go print extra output; unset them (GOFLAGS=)
2. Ensure the builder image's Go version is one supported by the fabric version
3. Run 'go list -m -json' manually in the chaincode dir to inspect raw output
4. Remove any go wrapper/shim scripts that prepend text to stdout

Example fix

// before
GOFLAGS="-mod=vendor -x"  (verbose output pollutes)
// after
GOFLAGS="-mod=vendor"

out, err := exec.Command("go", "list", "-m", "-json").Output()
if err != nil { return err }
if !json.Valid(out) { return fmt.Errorf("go list emitted non-JSON output: %s", out) }

When it happens

Trigger: moduleInfo -> listModuleInfo: the 'go list' subprocess output cannot be unmarshalled into the anonymous struct {Dir, ImportPath, GoMod, Module{...}} — e.g. go printed warnings/human text to stdout, or an ancient/odd go version emitted different JSON.

Common situations: GOFLAGS injecting extra output; wrapper scripts around go polluting stdout; very old Go toolchain in builder image; locale/encoding output mixed into the stream.

Understand the failure class

Background: "failed to unmarshal" / json.Unmarshal errors: why parsing a response into a Go struct fails and how to fix it — this error's family across 23 libraries.

Related errors

• too few arguments
• Failed opening file %s: %v
• config isn't valid
• incorrect number of arguments
• connection.json not found in source folder: %s

AI-assisted analysis of hyperledger/fabric@2736b63f8f (2026-09-04). Data as JSON: /api/errors/12448d57f5eb7fec. Report an issue: GitHub.