What causes "request failed with empty body" in vercel/next.js?

Retry the build (transient empty-body responses often clear on retry) — but change something (clean .next, retry once) per retry discipline.

vercel/next.js · error · Error

request failed with empty body

Error message

request failed with empty body

What it means

Thrown by download-swc.ts when the registry responded OK (2xx) but the response body stream is null/absent. Even though the status looked successful, there is no content to pipe to disk, so Next.js refuses to write an empty/corrupt tarball and aborts the SWC extraction.

Source

Thrown at packages/next/src/lib/download-swc.ts:51

      cacheDirectory,
      `${tarFileName}.temp-${Date.now()}`
    )

    const registry = getRegistry()

    const downloadUrl = `${registry}${pkgName}/-/${tarFileName}`

    await fetch(downloadUrl).then((res) => {
      const { ok, body } = res
      if (!ok || !body) {
        Log.error(`Failed to download swc package from ${downloadUrl}`)
      }

      if (!ok) {
        throw new Error(`request failed with status ${res.status}`)
      }
      if (!body) {
        throw new Error('request failed with empty body')
      }
      const cacheWriteStream = fs.createWriteStream(tempFile)
      return body.pipeTo(
        new WritableStream({
          write(chunk) {
            return new Promise<void>((resolve, reject) =>
              cacheWriteStream.write(chunk, (error) => {
                if (error) {
                  reject(error)
                  return
                }

                resolve()
              })
            )
          },
          close() {
            return new Promise<void>((resolve, reject) =>

View on GitHub (pinned to 0ae8c72462)

Solutions

Retry the build (transient empty-body responses often clear on retry) — but change something (clean .next, retry once) per retry discipline.
Point npm to a healthier registry mirror or bypass the corporate proxy for registry.npmjs.org.
Pre-install the @next/swc-<triple> package so the on-demand download path is never exercised.
Verify the proxy/CDN configuration preserves response bodies for binary package tarballs.

Example fix

# before
pnpm build  # 200 but empty body -> error
# after: pre-install so no fetch happens
pnpm add @next/swc-linux-x64-gnu
pnpm build

Defensive patterns

Strategy: retry

Validate before calling

// Verify the registry returns a non-empty body for the tarball HEAD
async function swcTarballHasBody(url: string): Promise<boolean> {
  const r = await fetch(url)
  return r.ok && Boolean(r.body)
}

Try / catch

async function downloadBody(url: string, attempts = 3) {
  for (let i = 0; i < attempts; i++) {
    const r = await fetch(url)
    if (r.ok && r.body) return r
    if (!r.ok) throw new Error(`status ${r.status}`)
    if (i === attempts - 1) throw new Error('request failed with empty body')
  }
  throw new Error('unreachable')
}

Prevention

Pre-install the SWC binary to bypass the download path entirely.
If behind a corporate proxy, validate it preserves binary response bodies.
Retry once with a fresh .next cache; report persistent empty bodies to the registry operator.
Prefer a registry mirror known to serve complete tarballs.

When it happens

Trigger: extractBinary() fetches the SWC tarball, res.ok is true but res.body is falsy. Happens with misbehaving proxies/CDNs that return 200 with no body, registries streaming errors inside a 200 envelope, or HTTP/2 intermediaries that drop the stream.

Common situations: Corporate proxies (Artifactory, Squid, Zscaler) that return 200 for HEAD-like requests or strip the body; a registry mirror that 200-redirects to a broken upstream; or a flaky CDN edge serving an empty response. Distinguished from [107] by the OK status.

Related errors

AI-assisted analysis of vercel/next.js@0ae8c72462 (2026-08-06). Data as JSON: /api/errors/c2f4944ae7cc974b. Report an issue: GitHub.