linshenkx/prompt-optimizer · error · RequestConfigError

Image at index ${index} is missing base64 data

Error message

Image at index ${index} is missing base64 data

What it means

Thrown by validateImageUnderstandingRequest when an image object's b64 field is not a string or is empty/whitespace-only. The adapter requires actual base64 image data for each entry; missing data means the request cannot be encoded. Client-side RequestConfigError that names the failing index.

Source

Thrown at packages/core/src/services/llm/adapters/abstract-adapter.ts:221

    if (!request || typeof request !== 'object') {
      throw new RequestConfigError('Image understanding request cannot be empty')
    }

    if (typeof request.userPrompt !== 'string' || !request.userPrompt.trim()) {
      throw new RequestConfigError('Image understanding user prompt cannot be empty')
    }

    if (!Array.isArray(request.images) || request.images.length === 0) {
      throw new RequestConfigError('Image understanding request requires at least one image')
    }

    request.images.forEach((image, index) => {
      if (!image || typeof image !== 'object') {
        throw new RequestConfigError(`Image at index ${index} is invalid`)
      }

      if (typeof image.b64 !== 'string' || !image.b64.trim()) {
        throw new RequestConfigError(`Image at index ${index} is missing base64 data`)
      }
    })
  }

  // ===== 工具方法 =====

  /**
   * 处理<think>标签，分离推理内容和主要内容
   * 从现有service.ts中的processStreamContentWithThinkTags逻辑迁移
   *
   * @param content 原始内容
   * @returns 处理后的结果 {content: 主要内容, reasoning?: 推理内容}
   */
  protected processThinkTags(content: string): { content: string; reasoning?: string } {
    // 如果内容不包含think标签，直接返回
    if (!content.includes('<think>')) {
      return { content }
    }

View on GitHub (pinned to 3e677b1d9f)

Solutions

1. Convert Buffers/ArrayBuffers explicitly: buffer.toString('base64')
2. Verify the property name is exactly b64 and that file reading succeeded before building the image object
3. Filter/validate entries with a guard checking typeof b64 === 'string' && b64.trim().length > 0

Example fix

// before
images: [{ b64: fileBuffer }]

// after
images: [{ b64: fileBuffer.toString('base64') }]

const images = request.images
  .filter(i => i && typeof i.b64 === 'string' && i.b64.trim().length > 0)
if (images.length === 0) throw new Error('no images with data')

function hasB64Data(i: unknown): i is { b64: string } {
  return !!i && typeof i === 'object'
    && typeof (i as { b64: string }).b64 === 'string'
    && (i as { b64: string }).b64.trim().length > 0
}

null

When it happens

Trigger: images[i].b64 is undefined, '', ' ', or a Buffer/Uint8Array instead of a base64 string; reading the wrong property name (base64, data) from an upload result.

Common situations: File-read step failed silently and b64 was never set; property name mismatch with backend response (data vs b64); passing a Buffer without .toString('base64').

Related errors

• Favorite metadata cannot contain inline image data URLs (${p
• Image understanding request cannot be empty
• Image understanding user prompt cannot be empty
• Image understanding request requires at least one image
• Image at index ${index} is invalid

AI-assisted analysis of linshenkx/prompt-optimizer@3e677b1d9f (2026-08-27). Data as JSON: /api/errors/29735ac74aa99ec5. Report an issue: GitHub.