semaphoreui/semaphore · error

err

Error message

err

What it means

SaveConfig panics with the raw error when the in-memory Semaphore config cannot be marshaled to JSON by config.ToJSON(). This happens only if the JSON encoding of the ConfigType struct fails, which is practically an internal invariant violation since the config struct consists of JSON-serializable fields. The panic is unguarded, so it crashes the setup command with a stack trace.

Solutions

1. Check the panic stack trace to identify the unmarshalable config field introduced by recent code changes
2. Ensure all fields of the ConfigType struct and nested types are JSON-serializable (no channels, funcs, or cyclic references)
3. Upgrade or downgrade Semaphore to a version whose config marshaling works; if the config was populated programmatically, validate it with config.ToJSON() in a recover-wrapped test first

Example fix

// before
bytes, err := config.ToJSON()
if err != nil {
	panic(err)
}
// after
bytes, err := config.ToJSON()
if err != nil {
	log.Fatalf("could not serialize config to JSON: %v", err)
}

if _, err := config.ToJSON(); err != nil {
	log.Fatalf("config not serializable: %v", err)
}

func isJSONSerializable(v any) bool {
	_, err := json.Marshal(v)
	return err == nil
}

func safeSave(cfg util.ConfigType) (err error) {
	defer func() {
		if r := recover(); r != nil {
			err = fmt.Errorf("SaveConfig panicked: %v", r)
		}
	}()
	SaveConfig(cfg, path)
	return nil
}

When it happens

Trigger: Calling doSetup or doRunnerSetup and having config.ToJSON() return an error during JSON marshaling of the assembled config object (e.g. an unsupported value type was injected into the config before marshaling).

Common situations: Custom builds or forks that added a field to the config struct that json.Marshal cannot serialize (channels, funcs, cyclic structures); corrupted intermediate config objects built programmatically via API instead of the interactive wizard.

Understand the failure class

Background: json.Marshal / "failed to marshal" errors in Go: why "unsupported type" happens and how to fix it — this error's family across 22 libraries.

Related errors

• err
• err
• err
• cannot assign value of type
• got non-existent config attribute

AI-assisted analysis of semaphoreui/semaphore@1774ccb71a (2026-09-07). Data as JSON: /api/errors/33290aa4d11338d8. Report an issue: GitHub.

Appendix: source

Thrown at cli/setup/setup.go:243

	fmt.Printf("Running: mkdir -p %v..\n", configDirectory)

	var err error

	if _, err = os.Stat(configDirectory); err != nil {
		if os.IsNotExist(err) {
			err = os.MkdirAll(configDirectory, 0755)
		}
	}

	if err != nil {
		log.Panic("Could not create config directory: " + err.Error())
	}

	// Marshal config to json
	bytes, err := config.ToJSON()
	if err != nil {
		panic(err)
	}

	if err = os.WriteFile(configPath, bytes, 0644); err != nil {
		panic(err)
	}

	fmt.Printf("Configuration written to %v..\n", configPath)
	return
}

func askValue(prompt string, defaultValue string, item any) {
	// Print prompt with optional default value
	fmt.Print(prompt)
	if len(defaultValue) != 0 {
		fmt.Print(" (default " + defaultValue + ")")
	}
	fmt.Print(": ")

View on GitHub (pinned to 1774ccb71a)