reserved-port.mdx
title: Reserved Port
Why This Error Occurred
Server was started on a reserved port. For example, 4045 is reserved for the Network Paging Protocol (npp).
next start -p 4045
or
next dev --port 4045
Starting the server on a reserved port will result in an error.
Possible Ways to Fix It
Change the provided port to ensure it's not listed in the Port Blocking section of WHATWG's fetch spec.
Useful Links
Rendered from the public repository vercel/next.js on GitHub; content belongs to its authors. Cached for up to an hour.