alibaba/nacos · error · IllegalArgumentException

Prompt is required

Error message

Prompt is required

What it means

Thrown by PromptOptimizationForm.validate() (copilot module) when the `prompt` field is null, empty, or whitespace-only. This form backs the POST /v3/console/copilot/prompt/optimize SSE endpoint. The original prompt is mandatory because the AI needs source material to optimize; optimizationGoal is optional.

Source

Thrown at copilot/src/main/java/com/alibaba/nacos/copilot/form/PromptOptimizationForm.java:44

public class PromptOptimizationForm {
    
    /**
     * Original Prompt content (required).
     */
    private String prompt;
    
    /**
     * Optimization goal/requirement description (optional).
     * e.g., "Make response more concise", "Add more examples", "Support multi-language"
     */
    private String optimizationGoal;
    
    /**
     * Validate form data.
     */
    public void validate() {
        if (StringUtils.isBlank(prompt)) {
            throw new IllegalArgumentException("Prompt is required");
        }
    }
    
    public String getPrompt() {
        return prompt;
    }
    
    public void setPrompt(String prompt) {
        this.prompt = prompt;
    }
    
    public String getOptimizationGoal() {
        return optimizationGoal;
    }
    
    public void setOptimizationGoal(String optimizationGoal) {
        this.optimizationGoal = optimizationGoal;
    }

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Send a non-blank `prompt` string in the request body.
2. Keep the client-side trim guard and replicate it for any API client.
3. If the prompt comes from a variable, ensure it resolves to non-empty content.

Example fix

// before
body: JSON.stringify({ prompt: template, optimizationGoal: optimizeGoal })

// after
if (!template.trim()) {
  setOptimizeError('Prompt template is empty');
  return;
}
body: JSON.stringify({ prompt: template, optimizationGoal: optimizeGoal })

function hasPrompt(prompt: unknown): boolean {
  return typeof prompt === 'string' && prompt.trim().length > 0;
}

When it happens

Trigger: Posting to /v3/console/copilot/prompt/optimize with an empty/whitespace/null `prompt` field. The front-end handlers guard `if (!template.trim()) return;` but direct API callers can send an empty prompt.

Common situations: User clears the template then clicks optimize. Programmatic call with an empty prompt body. Template variable resolving to empty.

Related errors

• Prompt is required
• User input is required
• Background information is required
• Skill is required
• Skill name is required

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/a46321569437f5d2. Report an issue: GitHub.