Issue :-
had created project in ionic v4 and I got error in ./src/global.scss, see error in the below
>ERROR in ./src/global.scss (./node_modules/@angular-devkit/build-angular/src/angular-cli-files/plugins/raw-css-loader.js!./node_modules/postcss-loader/src??embedded!./node_modules/sass-loader/lib/loader.js??ref--14-3!./src/global.scss)
[ng] Module build failed (from ./node_modules/sass-loader/lib/loader.js):
[ng] Error: Cannot find module 'node-sass'
[ng] at Function.Module._resolveFilename (internal/modules/cjs/loader.js:581:15)
[ng] at Function.Module._load (internal/modules/cjs/loader.js:507:25)
[ng] at Module.require (internal/modules/cjs/loader.js:637:17)
[ng] at require (internal/modules/cjs/helpers.js:22:18)
[ng] at Object.sassLoader (/home/manish/newionic_workspace/latest100days/node_modules/sass-loader/lib/loader.js:46:72)
[ng] ERROR in ./src/theme/variables.scss (./node_modules/@angular-devkit/build-angular/src/angular-cli-files/plugins/raw-css-loader.js!./node_modules/postcss-loader/src??embedded!./node_modules/sass-loader/lib/loader.js??ref--14-3!./src/theme/variables.scss)
[ng] Module build failed (from ./node_modules/sass-loader/lib/loader.js):
[ng] Error: Cannot find module 'node-sass'
[ng] at Function.Module._resolveFilename (internal/modules/cjs/loader.js:581:15)
[ng] at Function.Module._load (internal/modules/cjs/loader.js:507:25)
[ng] at Module.require (internal/modules/cjs/loader.js:637:17)
[ng] at require (internal/modules/cjs/helpers.js:22:18)
[ng] at Object.sassLoader (/home/manish/newionic_workspace
/latest100days/node_modules/sass-loader/lib/loader.js:46:72)
Solution :-
Use npm install --save-dev node-sass
or npm rebuild node-sass --force
For Linux Users :-
You have to give global permission first, add sudo at the beggining.
sudo npm i node-sass
Hope this works for you too!