Error when running grunt exec

Question

I have followed the docs for setting up Less compilation. Running grunt clean and grunt less works without errors, but when I run grunt exec (with or without appending a specific theme name) I get the following error:

Execution Time (2018-03-09 15:33:35 UTC)
loading tasks                55ms  ▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇▇ 58%
loading grunt-contrib-clean   3ms  ▇▇ 3%
clean:mytheme           37ms  ▇▇▇▇▇▇▇▇▇▇▇▇▇ 39%
Total 95ms

>> Exited with code: 255.
>> Error executing child process: Error: Process exited with code 255.
Warning: Task "exec:mytheme" failed. Use --force to continue.

I've tried so many different things to get this working but to no avail. Has anyone encountered this before?

My dev/tools/grunt/configs/themes.js has this added:

mytheme: {
    area: 'frontend',
    name: 'Mycompany/mytheme',
    locale: 'en_US',
    files: [
        'css/styles-m',
        'css/styles-l'
    ],
    dsl: 'less'
}

And my Gruntfile.js and package.json files are the same as those included with v2.2.2 (the sample files renamed).

Answer 1

Try to use another node version. Node version is 10.10.0 but i returned to 8.12.0 and works.

You can change with this https://github.com/creationix/nvm

Answer 2

In my experience this happens when Grunt can't access the database. Make sure:

• You are running this from inside your Magento SSH terminal
• Your Magento instance running and has a working DB

If both of those are true, what happens if you run php bin/magento dev:source-theme:deploy --type=less --locale=en_US --area=frontend --theme=Mycompany/mytheme?