vercel/ai · error · Error

Prodia response missing multipart boundary in content-type:

Error message

Prodia response missing multipart boundary in content-type: ${contentType}

What it means

The Prodia language model expects the provider API to answer image-generation jobs with a multipart response whose content-type header declares a boundary (e.g. multipart/form-data; boundary=...). The handler parses that boundary out of the header to split the body into the job JSON part and the output part. If the content-type header is absent or contains no boundary parameter, the body cannot be split, so the SDK fails fast with this error instead of producing a corrupt parse.

Source

Thrown at packages/prodia/src/prodia-language-model.ts:377

function createLanguageMultipartResponseHandler() {
  return async ({
    response,
  }: {
    response: Response;
  }): Promise<{
    value: LanguageMultipartResult;
    responseHeaders: Record<string, string>;
  }> => {
    const contentType = response.headers.get('content-type') ?? '';
    const responseHeaders: Record<string, string> = {};
    response.headers.forEach((value, key) => {
      responseHeaders[key] = value;
    });

    const boundaryMatch = contentType.match(/boundary=([^\s;]+)/);
    if (!boundaryMatch) {
      throw new Error(
        `Prodia response missing multipart boundary in content-type: ${contentType}`,
      );
    }
    const boundary = boundaryMatch[1];

    const arrayBuffer = await response.arrayBuffer();
    const bytes = new Uint8Array(arrayBuffer);

    const parts = parseMultipart(bytes, boundary);

    let jobResult: ProdiaJobResult | undefined;
    let textContent: string | undefined;
    const fileContent: Array<{ mediaType: string; data: Uint8Array }> = [];

    for (const part of parts) {
      const contentDisposition = part.headers['content-disposition'] ?? '';
      const partContentType = part.headers['content-type'] ?? '';

View on GitHub (pinned to 69428b1f8b)

Solutions

1. Verify your Prodia API key and that the request reached the correct Prodia endpoint (inspect responseHeaders captured by the SDK).
2. Log the full content-type value from the error message to see what the server actually returned (e.g. application/json usually means an API error body).
3. Check for proxies, gateways, or service workers between your app and Prodia that strip or rewrite the content-type header.
4. Confirm you are on a current @ai-sdk/prodia version and the Prodia API contract still returns multipart for this model.

Example fix

// before: trusting the server response shape
const result = await model.doGenerate({ ... });

// after: pre-flight a direct call to catch non-multipart API errors early
const res = await fetch('https://api.prodia.com/v1/...', { headers: { authorization: `Bearer ${key}` } });
const ct = res.headers.get('content-type') ?? '';
if (!ct.includes('boundary=')) {
  console.error('Prodia returned non-multipart response:', await res.text());
}

const ct = response.headers.get('content-type') ?? '';
if (!/^multipart\//i.test(ct) || !/boundary=/i.test(ct)) {
  throw new Error(`Expected multipart response with boundary, got: ${ct}`);
}

function hasMultipartBoundary(contentType: string): boolean {
  return /boundary=([^\s;]+)/.test(contentType);
}

try {
  const result = await model.doGenerate({ ... });
} catch (error) {
  if (error instanceof Error && error.message.includes('missing multipart boundary')) {
    // inspect/log raw response content-type; likely an API error body
  }
  throw error;
}

When it happens

Trigger: A doGenerate call on the Prodia language model where the HTTP response's content-type header is missing, is not multipart (e.g. application/json or text/html), or is multipart but lacks the boundary= parameter — typically because a proxy, gateway, or an error page intercepted the response.

Common situations: Prodia API returning a JSON error envelope with 200/4xx status instead of multipart; corporate proxies or CDNs rewriting content-type headers; hitting a wrong endpoint or an API-version mismatch; an expired/blocked API key causing the server to return an HTML error page.

Related errors

• Prodia multipart response missing job part
• Prodia response missing multipart boundary in content-type:
• Prodia multipart response missing job part
• Prodia multipart response missing output video
• No speech audio generated.

AI-assisted analysis of vercel/ai@69428b1f8b (2026-08-30). Data as JSON: /api/errors/c1e8c7b64415e2f9. Report an issue: GitHub.