What causes "error getting prompt config: %v" in Billionmail/BillionMail?

Inspect the wrapped inner message to identify the real cause (read vs unmarshal vs save)

error getting prompt config

Error message

error getting prompt config: %v

What it means

ModifyPrompt calls GetPrompt first to load the existing PromptConfig for the domain; this wrapper re-surfaces any GetPrompt failure (missing-and-uncreatable file, unreadable file, or corrupt JSON) prefixed with 'error getting prompt config'. It means the update could not even start because the current config could not be loaded.

Solutions

Inspect the wrapped inner message to identify the real cause (read vs unmarshal vs save)
Fix the underlying prompt_config.json (validate with jq) or delete it so GetPrompt regenerates the default
Verify PRODUCT_CONFIG_PATH exists and is writable by the process user (check volume mounts in Docker)
Run as a user with read/write access to the config directory

Example fix

// before
$ docker volume not mounted
error getting prompt config: error reading prompt config file: open /app/config/mydomain.com/prompt_config.json: no such file or directory

// after
# mount the config volume
volumes:
  - ./config:/app/config

Defensive patterns

Strategy: try-catch

Validate before calling

// ensure the config dir exists and is writable before ModifyPrompt
dir := filepath.Join(PRODUCT_CONFIG_PATH, domain)
if err := os.MkdirAll(dir, os.ModePerm); err != nil {
	return fmt.Errorf("config dir unavailable: %w", err)
}
if f, err := os.CreateTemp(dir, ".wtest"); err != nil {
	return fmt.Errorf("config dir not writable: %w", err)
} else {
	f.Close(); os.Remove(f.Name())
}

Try / catch

if err := ModifyPrompt(domain, prompt); err != nil {
	var inner error
	if strings.Contains(err.Error(), "unmarshalling") {
		// recover from corrupt config by regenerating defaults
		os.Remove(filepath.Join(PRODUCT_CONFIG_PATH, domain, "prompt_config.json"))
		inner = ModifyPrompt(domain, prompt)
	} else {
		inner = err
	}
	if inner != nil {
		log.Printf("ModifyPrompt failed for %s: %v", domain, inner)
	}
}

Prevention

Mount a writable volume at PRODUCT_CONFIG_PATH in containers
Run the app as a user that owns the config directory
Monitor config-dir permissions after deployment changes
Regenerate default config files when they fail to parse instead of failing hard

When it happens

Trigger: Calling ModifyPrompt(domain, newPrompt) when the domain's prompt_config.json is unreadable (permissions) or contains invalid JSON (error 195), or PRODUCT_CONFIG_PATH/<Domain> cannot be created on first use.

Common situations: Corrupt config from an earlier failed write; wrong PRODUCT_CONFIG_PATH configured for the deployment (config dir not mounted in Docker); file owned by root while the app runs as another user.

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

AI-assisted analysis of Billionmail/BillionMail@fc36c76c05 (2026-09-05). Data as JSON: /api/errors/f7ce62812fc3ebba. Report an issue: GitHub.

Appendix: source

Thrown at core/internal/service/askai/project.go:818

	if err != nil {
		return PromptConfig{}, fmt.Errorf("error reading prompt config file: %v", err)
	}

	var config PromptConfig
	err = json.Unmarshal(data, &config)
	if err != nil {
		return PromptConfig{}, fmt.Errorf("error unmarshalling prompt config: %v", err)
	}
	return config, nil
}

// ModifyPrompt updates the prompt configuration for a given domain.
// It reads the existing prompt configuration, modifies the specified fields, and saves the updated configuration back to the file.
// If the prompt is empty, it will not be updated.
func ModifyPrompt(Domain string, Prompt string) error {
	config, err := GetPrompt(Domain)
	if err != nil {
		return fmt.Errorf("error getting prompt config: %v", err)
	}

	// Update the prompt configuration
	if Prompt != "" {
		config.Prompt = Prompt
	}

	config.UpdateTime = public.GetNowTime()
	filename := fmt.Sprintf(PRODUCT_CONFIG_PATH+"/%s/prompt_config.json", Domain)
	data, err := json.Marshal(config)
	if err != nil {
		return fmt.Errorf("error marshalling prompt config: %v", err)
	}
	err = os.WriteFile(filename, data, 0644)
	if err != nil {
		return fmt.Errorf("error saving prompt config file: %v", err)
	}
	return nil

View on GitHub (pinned to fc36c76c05)