anomalyco/sst · error

failed to load cloudflare unenv config: %w %s

Error message

failed to load cloudflare unenv config: %w
%s

What it means

The worker (Cloudflare Workers) runtime determines Node.js compat polyfills by spawning `node src/runtime/worker/unenv.mjs` with the project's compatibility flags. This error means the child Node process exited non-zero; the script's combined stdout/stderr is appended to help diagnose why. unenv config resolution is required before esbuild can bundle, so the build aborts.

Source

Thrown at pkg/runtime/worker/worker.go:261

	w.lock.RLock()
	if cached, ok := w.unenv[key]; ok {
		w.lock.RUnlock()
		return cached, nil
	}
	w.lock.RUnlock()

	cmd := process.CommandContext(
		ctx,
		"node",
		filepath.Join(path.ResolvePlatformDir(cfgPath), "src/runtime/worker/unenv.mjs"),
		string(payload),
	)
	cmd.Dir = path.ResolvePlatformDir(cfgPath)
	cmd.Env = []string{}
	output, err := cmd.CombinedOutput()
	if err != nil {
		return nil, fmt.Errorf("failed to load cloudflare unenv config: %w\n%s", err, output)
	}

	var result unenv
	if err := json.Unmarshal(output, &result); err != nil {
		return nil, fmt.Errorf("failed to decode cloudflare unenv config: %w\n%s", err, output)
	}

	w.lock.Lock()
	w.unenv[key] = &result
	w.lock.Unlock()

	return &result, nil
}

func (w *Runtime) Match(runtime string) bool {
	return runtime == "worker"
}

View on GitHub (pinned to a0bd20f762)

Solutions

1. Ensure `node` (>=18) is installed and on PATH: `node -v`
2. Delete `.sst/` and reinstall platform deps (`bun install` / `npm install` in the platform dir), then retry
3. Check your `worker` component's `compatibilityDate`/`compatibilityFlags` values against valid Cloudflare dates
4. Run the script manually to see the full error: `cd .sst/platform/src/runtime/worker && node unenv.mjs '{}'`

Example fix

// before (sst.config.ts)
compatibilityDate: "2099-01-01"
// after
compatibilityDate: "2025-01-01"

// before deploy, ensure node is available and the platform script exists
execSync("node -v", { stdio: "inherit" });
const script = path.join(".sst/platform/src/runtime/worker/unenv.mjs");
if (!fs.existsSync(script)) throw new Error("platform not installed; run sst setup / reinstall");

try {
  await run("sst", ["deploy"]);
} catch (e) {
  if (/failed to load cloudflare unenv config/.test(String(e))) {
    console.error("unenv.mjs failed; output was:\n" + String(e).split("\n").slice(1).join("\n"));
    // common remedy: reinstall platform deps
    await exec("rm", ["-rf", ".sst"]);
    await run("sst", ["deploy"]); // or instruct user to reinstall
  } else throw e;
}

When it happens

Trigger: Running `sst deploy`/`sst dev` for a `worker` runtime component when the spawned `node unenv.mjs` fails: node not on PATH, the script throws (missing `unenv` dependency in the platform dir), or an invalid `compatibility_date`/`compatibility_flags` payload.

Common situations: No Node.js installed or wrong version on the machine; corrupted or partially installed `node_modules` under `.sst/platform`; unsupported compatibility date string passed in `sst.config.ts`; empty `cmd.Env` hiding needed env vars.

Related errors

• failed to decode cloudflare unenv config: %w %s
• Invalid worker definition for the "${name}" Worker
• not implemented
• Build metadata file not found at "${filePath}". Update your
• Build ID not found in ".next/BUILD_ID" for site "${name}". E

AI-assisted analysis of anomalyco/sst@a0bd20f762 (2026-08-30). Data as JSON: /api/errors/cfc552c9593a6b09. Report an issue: GitHub.