vercel/next.js · error · Error

Certificate files not found

Error message

Certificate files not found

What it means

Post-run verification in createSelfSignedCertificate: mkcert was executed with -install and exited without error, but the expected key and/or certificate files were still not written to disk. The tool's exit status lied about success, so Next.js re-checks the filesystem before trusting the result.

Source

Thrown at packages/next/src/lib/mkcert.ts:155

    const defaultHosts = ['localhost', '127.0.0.1', '::1']

    const hosts =
      host && !defaultHosts.includes(host)
        ? [...defaultHosts, host]
        : defaultHosts

    execSync(
      `"${binaryPath}" -install -key-file "${keyPath}" -cert-file "${certPath}" ${hosts.join(
        ' '
      )}`,
      { stdio: 'ignore' }
    )

    const caLocation = execSync(`"${binaryPath}" -CAROOT`).toString().trim()

    if (!fs.existsSync(keyPath) || !fs.existsSync(certPath)) {
      throw new Error('Certificate files not found')
    }

    Log.info(`CA Root certificate created in ${caLocation}`)
    Log.info(`Certificates created in ${resolvedCertDir}`)

    const gitignorePath = path.resolve(process.cwd(), './.gitignore')

    if (fs.existsSync(gitignorePath)) {
      const gitignore = await fs.promises.readFile(gitignorePath, 'utf8')
      if (!gitignore.includes(certDir)) {
        Log.info('Adding certificates to .gitignore')

        await fs.promises.appendFile(gitignorePath, `\n${certDir}`)
      }
    }

    return {
      key: keyPath,

View on GitHub (pinned to 0eb3775416)

Solutions

1. Re-run the certificate generation (next dev --experimental-https) so the cert files are created.

When it happens

Trigger: mkcert ran but the generated certificate files are not found.

Common situations: Certificate generation failed silently or files were written to an unexpected location.

Understand the failure class

• SSL/TLS and certificate errors — how TLS handshakes and certificate validation fail.

AI-assisted analysis of vercel/next.js@0eb3775416 (2026-08-19). Data as JSON: /api/errors/4af82f111ab5cb9c. Report an issue: GitHub.