linshenkx/prompt-optimizer · error · EvaluationValidationError

${label} content must not be empty.

Error message

${label} content must not be empty.

What it means

A content block must contain actual material: either non-empty text content or at least one media attachment (checked via hasBlockMedia). This error fires when the block has a label but both content and media are absent/blank, leaving an empty shell the evaluation cannot execute.

Source

Thrown at packages/core/src/services/evaluation/service.ts:1705

        );
      }
    });
  }

  private validateContentBlock(
    block: EvaluationContentBlock | undefined,
    label: string
  ): void {
    if (!block) {
      throw new EvaluationValidationError(`${label} must not be empty.`);
    }
    if (!block.label?.trim()) {
      throw new EvaluationValidationError(`${label} label must not be empty.`);
    }
    const hasContent = !!block.content?.trim();
    const hasMedia = this.hasBlockMedia(block);
    if (!hasContent && !hasMedia) {
      throw new EvaluationValidationError(`${label} content must not be empty.`);
    }
    if (block.media) {
      this.validateMediaItems(block.media, `${label} media`);
    }
  }

  private validateTestCase(testCase: EvaluationTestCase | undefined, label: string): void {
    if (!testCase?.id?.trim()) {
      throw new EvaluationValidationError(`${label} id must not be empty.`);
    }
    this.validateContentBlock(testCase.input, `${label} input`);
  }

  private validateSnapshot(snapshot: EvaluationSnapshot | undefined, label: string): void {
    if (!snapshot?.id?.trim()) {
      throw new EvaluationValidationError(`${label} id must not be empty.`);
    }
    if (!snapshot?.label?.trim()) {

View on GitHub (pinned to 3e677b1d9f)

Solutions

1. Populate block.content with the prompt text, or attach at least one valid media item
2. If media was intended, verify the media array survived serialization and items pass validateMediaItems
3. Guard submissions with a client-side emptiness check

Example fix

// before
input: { label: 'prompt', content: '   ' }

// after
input: { label: 'prompt', content: 'Describe the attached image.', media: [{ label: 'img', assetId: 'img-1' }] }

function blockHasMaterial(block: { content?: string; media?: unknown[] }): boolean {
  return !!block.content?.trim() || (block.media?.some(m => !!m?.assetId?.trim() || !!m?.b64?.trim()) ?? false);
}

const isNonEmptyBlock = (b: { content?: string; media?: unknown[] } | undefined): boolean =>
  !!b?.content?.trim() || !!b?.media?.length;

try {
  await evaluationService.create(request);
} catch (err) {
  if (err instanceof EvaluationValidationError && /content must not be empty/.test(err.message)) {
    removeOrFillEmptyBlock(err.message);
  } else throw err;
}

When it happens

Trigger: A content block such as { label: 'prompt' } with no content and no media array (or media: []). Also fires when content is whitespace-only and media is empty.

Common situations: Front-end forms allowing submit with only a label; trimming content to empty before submission; media items lost during serialization so media becomes [].

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• ${label} must not be empty.
• ${label} label must not be empty.
• Unrecognized data structure
• Result evaluation snapshot testCaseId must match testCase.id
• Image result evaluation requires at least one output image e

AI-assisted analysis of linshenkx/prompt-optimizer@3e677b1d9f (2026-08-27). Data as JSON: /api/errors/b72f44511995eeaf. Report an issue: GitHub.