What causes "spawn is not supported in Cloudflare Workers" in DIYgod/RSSHub?

Do not invoke spawn() in Worker-deployed routes.

spawn is not supported in Cloudflare Workers

Error message

spawn is not supported in Cloudflare Workers

What it means

Intentional guard in the Workers shim (lib/shims/node-child-process.ts). spawn() has no Workers equivalent (no subprocess capability), so it throws on call. Like exec(), it is fail-fast; only execSync() is stubbed with an empty-Buffer fallback.

Source

Thrown at lib/shims/node-child-process.ts:14

// Worker-specific shim for node:child_process
// This module is not available in Cloudflare Workers

export function execSync(_command: string): Buffer {
    // Return empty buffer - git info will fall back to 'unknown'
    return Buffer.from('');
}

export function exec() {
    throw new Error('exec is not supported in Cloudflare Workers');
}

export function spawn() {
    throw new Error('spawn is not supported in Cloudflare Workers');
}

View on GitHub (pinned to bed535e087)

Solutions

Do not invoke spawn() in Worker-deployed routes.
Detect the runtime and branch to a Workers-compatible alternative (e.g. fetch-based).
Run that route on the Node target instead of Workers.

Example fix

// before
import { spawn } from 'node:child_process';
const p = spawn('ffmpeg', ['-i', url]);
// after — under Workers, fetch the media URL directly instead of spawning ffmpeg
const buf = await fetch(url).then((r) => r.arrayBuffer());

Defensive patterns

Strategy: validation

Validate before calling

function canSpawn(): boolean {
  return typeof process !== 'undefined' && !!process.versions?.node;
}
if (!canSpawn()) {
  // do not call spawn(); use fetch/stream APIs
}

Type guard

function isWorkersShimError(e: unknown): e is Error {
  return e instanceof Error && /not supported in Cloudflare Workers/.test(e.message);
}

Try / catch

try {
  if (canSpawn()) spawnTool(args);
} catch (e) {
  if (isWorkersShimError(e)) return fallbackStream();
  throw e;
}

Prevention

Never call spawn() in routes that may run on Workers.
Use fetch()/ReadableStream for I/O instead of subprocess streaming.
Reserve subprocess routes for the Node deployment target.

When it happens

Trigger: Calling child_process.spawn(...) under the Workers build — typically a long-running subprocess, streaming tool, or a dependency that spawns helpers.

Common situations: Puppeteer/Playwright-style process launching; media tool wrappers (ffmpeg); a Node-only utility route deployed to Workers.

Related errors

AI-assisted analysis of DIYgod/RSSHub@bed535e087 (2026-08-12). Data as JSON: /api/errors/16c4c8ba093bd2b8. Report an issue: GitHub.