[SOLVED] npm run watch error thanks to node version: Error: You are using an unsupported version of Node. Please update to at least Node v12.14

Hi all, I'm struggling with nodejs and npm in Laravel 8.0. If I do npm run watch I obtain this:

npm run watch

> @ watch /home/ottaviane/Sviluppo/exams
> mix watch

Error: You are using an unsupported version of Node. Please update to at least Node v12.14
    at assertSupportedNodeVersion (/home/ottaviane/Sviluppo/exams/node_modules/laravel-mix/src/Engine.js:6:15)
    at executeScript (/home/ottaviane/Sviluppo/exams/node_modules/laravel-mix/bin/cli.js:61:5)
    at Command.program.command.description.option.option.action (/home/ottaviane/Sviluppo/exams/node_modules/laravel-mix/bin/cli.js:39:13)
    at Command.listener [as _actionHandler] (/home/ottaviane/Sviluppo/exams/node_modules/commander/index.js:922:31)
    at Command._parseCommand (/home/ottaviane/Sviluppo/exams/node_modules/commander/index.js:1503:14)
    at Command._dispatchSubcommand (/home/ottaviane/Sviluppo/exams/node_modules/commander/index.js:1443:18)
    at Command._parseCommand (/home/ottaviane/Sviluppo/exams/node_modules/commander/index.js:1460:12)
    at Command.parse (/home/ottaviane/Sviluppo/exams/node_modules/commander/index.js:1292:10)
    at Command.parseAsync (/home/ottaviane/Sviluppo/exams/node_modules/commander/index.js:1318:10)
    at run (/home/ottaviane/Sviluppo/exams/node_modules/laravel-mix/bin/cli.js:50:19)
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! @ watch: `mix watch`
npm ERR! Exit status 1
npm ERR! 
npm ERR! Failed at the @ watch script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:
npm ERR!     /home/ottaviane/.npm/_logs/2022-01-23T17_13_11_178Z-debug.log

it seem a problem related to Node version, so I did:

nvm install v12.14
nvm use v12.14.1 
Now using node v12.14.1 (npm v6.13.4)

but still have the same problem! Help me please. Thank you very mutch. Bye.