Firebase is a backend platform to build web, mobile apps. It provides a realtime database, different authentications and a hosting platform. If you get one of the following error messages when you run Firebase, you can easily resolve the problem by switching to another version of Firebase tools.
Port 5000 is not open, could not start functions emulator. Port 5001 is not open, could not start functions emulator.
If you are using version 6 of Firebase Tools, you might switch to latest version (6.12.0), or you might try v7.2.2. To change to Firebase Tools version run to following node package manager command.
npm install -g email@example.com