grunt magento2 warning sign shows magento command

I got a problem using grunt

The warning sign is

jit-grunt: Plugin for the "&&" task not found.
If you have installed the plugin already, please setting the static mapping.
See https://github.com/shootaroo/jit-grunt#static-mappings

Warning: Task "&&" failed. Used --force, continuing.

jit-grunt: Plugin for the "php" task not found.
If you have installed the plugin already, please setting the static mapping.
See https://github.com/shootaroo/jit-grunt#static-mappings

Warning: Task "php" failed. Used --force, continuing.

jit-grunt: Plugin for the "bin/magento" task not found.
If you have installed the plugin already, please setting the static mapping.
See https://github.com/shootaroo/jit-grunt#static-mappings

Warning: Task "bin/magento" failed. Used --force, continuing.

jit-grunt: Plugin for the "dev" task not found.
If you have installed the plugin already, please setting the static mapping.
See https://github.com/shootaroo/jit-grunt#static-mappings

Warning: Task "dev:source-theme:deploy" failed. Used --force, continuing.

jit-grunt: Plugin for the "css/styles-m" task not found.
If you have installed the plugin already, please setting the static mapping.
See https://github.com/shootaroo/jit-grunt#static-mappings

Warning: Task "css/styles-m" failed. Used --force, continuing.

Done, but with warnings.

It’s done but It doesn’t convert less into css

When I take a look at combo.js file, the tasks above which is “&&”, “php”, “bin/magento” is there as a part of command

Please help

Answer

Grunt fails because it tries to execute two commands joined by double ampersand &&.

This is a bug that appears in grunt-exec 2.0.0. Upgrading to 3.0.0 didn’t help me, but downgrading to ~1.0.0 fixed the problem.

Edit package.json so the line for grunt-exec reads:

"grunt-exec": "~1.0.0",

Then run npm-update to download the older version of the package. Grunt should work after that.