alibaba/nacos · error · IllegalArgumentException

Skill is required

Error message

Skill is required

What it means

Thrown by SkillOptimizationForm.validate() (copilot module) when the `skill` field is null. This form backs the POST /v3/console/copilot/skill/optimize SSE endpoint. The entire Skill object must be present (not just non-null) because the optimizer needs the full skill structure including its name to operate.

Source

Thrown at copilot/src/main/java/com/alibaba/nacos/copilot/form/SkillOptimizationForm.java:66

    /**
     * Conversation history (optional).
     * Contains user inputs, tool calls, and model responses.
     */
    private ConversationHistory conversationHistory;
    
    /**
     * Target file name to optimize (optional).
     * If specified, only optimize the content of this specific file.
     * If not specified, optimize the entire Skill.
     */
    private String targetFileName;
    
    /**
     * Validate form data.
     */
    public void validate() {
        if (skill == null) {
            throw new IllegalArgumentException("Skill is required");
        }
        if (StringUtils.isBlank(skill.getName())) {
            throw new IllegalArgumentException("Skill name is required");
        }
    }
    
    public Skill getSkill() {
        return skill;
    }
    
    public void setSkill(Skill skill) {
        this.skill = skill;
    }
    
    public String getOptimizationGoal() {
        return optimizationGoal;
    }
    

View on GitHub (pinned to 9b989acdf1)

Solutions

1. Include a non-null `skill` object in the request body.
2. Ensure the skill is loaded/selected in the UI before enabling optimize.
3. Serialize the full Skill model (with at least a name) before posting.

Example fix

// before
body: JSON.stringify({ skill: currentSkill, optimizationGoal })

// after
if (!currentSkill) {
  setError('Select or load a skill to optimize');
  return;
}
body: JSON.stringify({ skill: currentSkill, optimizationGoal })

function hasSkill(skill: unknown): boolean {
  return skill !== null && skill !== undefined && typeof skill === 'object';
}

function isSkillLike(value: unknown): value is { name: string } {
  return value !== null && typeof value === 'object' && 'name' in value;
}

When it happens

Trigger: Posting to /v3/console/copilot/skill/optimize with the `skill` field omitted or explicitly null in the JSON body. optimizationGoal, selectedMcpTools, conversationHistory, and targetFileName are all optional.

Common situations: Client serializes a null skill reference. Form submitted before a skill is selected/loaded. API caller omits the skill object.

Related errors

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

AI-assisted analysis of alibaba/nacos@9b989acdf1 (2026-08-14). Data as JSON: /api/errors/67a12d96f12631e7. Report an issue: GitHub.