How to upgrade my global vue-cli install to the latest version?

For anyone still having this issue I ran through the following steps:

1. Switched to latest stable Node.js release using Node Version Manager

   nvm install 14.16.0

2. Uninstalled previous @vue/cli package

   npm uninstall -g @vue/cli

   npm uninstall -g vue-cli (v2.* and older)

3. Globally installed latest stable release

   npm install -g @vue/cli@latest

4. Opened a new terminal window for the change to take effect; checked the version by running below command

   vue --version

Kudos to Antony for his original answer.

vue-cli 3.x is changed to @vue/cli. Therefore, no direct upgrade exists.

1. Uninstall old version if you no longer need it, or if latest install command gives error:

npm uninstall -g vue-cli

2. Use the following command to install the latest vue-cli version:

$ npm install -g @vue/cli@latest

Notes

1. Do not run $ npm i -g vue-cli because vue-cli 3.x is changed to @vue/cli.

2. The vue-cli update issue states that either npm or yarn can be used to upgrade vue-cli. However, when working within nvm, the yarn command yarn global add @vue/cli did not work. If you do not use nvm then installing via yarn might work. However, I did not verify this.