jackwener/OpenCLI · error · CommandExecutionError

Midjourney media download returned an empty file from ${url}

Error message

Midjourney media download returned an empty file from ${url}

What it means

The download produced zero bytes (or a non-integer/non-positive size), so the file would be empty. The library treats empty payloads as a hard failure rather than writing a 0-byte file to disk.

Source

Thrown at clis/midjourney/utils.js:564

        return {
          ok: true,
          status: response.status,
          type: response.headers.get('content-type') || '',
          size: bytes.length,
        };
      }, url, transferKey));
    } catch (error) {
      throw new CommandExecutionError(`Midjourney browser-context media fetch failed: ${errorMessage(error)}`);
    }
    if (!payload || typeof payload !== 'object' || !payload.ok) {
      throw new CommandExecutionError(`Midjourney media download failed: HTTP ${payload?.status ?? 0} from ${url}`);
    }
    if (!String(payload.type || '').startsWith(expectedMimePrefix)) {
      throw new CommandExecutionError(`Midjourney media download returned unexpected content type "${payload.type || 'unknown'}"`);
    }
    const size = Number(payload.size);
    if (!Number.isInteger(size) || size <= 0) {
      throw new CommandExecutionError(`Midjourney media download returned an empty file from ${url}`);
    }

    // Returning a complete base64 file in one Browser Bridge response can
    // exceed the daemon message limit. Pull it out in bounded chunks instead.
    const parts = [];
    const chunkSize = 96 * 1024;
    for (let offset = 0; offset < size; offset += chunkSize) {
      const base64 = unwrapEvaluateResult(await page.evaluate((key, start, length) => {
        const bytes = window[key];
        if (!(bytes instanceof Uint8Array)) return null;
        const chunk = bytes.subarray(start, Math.min(bytes.length, start + length));
        let binary = '';
        const binaryChunkSize = 0x8000;
        for (let index = 0; index < chunk.length; index += binaryChunkSize) {
          binary += String.fromCharCode(...chunk.subarray(index, index + binaryChunkSize));
        }
        return btoa(binary);
      }, transferKey, offset, chunkSize));

View on GitHub (pinned to 49907e53dc)

Solutions

Retry the download; often transient.
Check the job status first to confirm the media actually exists.
Re-resolve the media URL and verify it serves bytes (e.g. via curl).
Wait until the job fully completes before downloading.

Defensive patterns

Strategy: retry

Validate before calling

const res = await fetch(url, { method: 'HEAD' });
const len = Number(res.headers.get('content-length') || 0);
if (!len) throw new Error('No content at ' + url + '; job media may not exist yet');

Try / catch

try {
  await downloadMedia(page, url);
} catch (err) {
  if (/empty file/.test(err.message)) {
    await sleep(5000);
    await downloadMedia(page, url); // transient empty responses often resolve
  } else throw err;
}

Prevention

Confirm the job reached a completed status before downloading.
Retry with delay; empty 200s from CDNs are frequently transient.
Verify the URL serves bytes out-of-band (curl -I) when debugging.
Avoid downloading immediately at job creation time.

When it happens

Trigger: The CDN returned HTTP 200 with an empty body; the in-page buffer reported a size of 0 or a non-numeric size; a redirect to an empty resource.

Common situations: Midjourney CDN serving empty responses for just-deleted or not-yet-finished media; transient CDN faults; fetching media for a job whose generation silently failed.

Related errors

AI-assisted analysis of jackwener/OpenCLI@49907e53dc (2026-08-29). Data as JSON: /api/errors/1fc32333080e1934. Report an issue: GitHub.