Gulp not working, throwing an error?

Question

Sass

installed correctly, I run the code in the gulpfile.js file taken from the browsersync website, here is the code:

var gulp        = require('gulp');
var browserSync = require('browser-sync').create();
var sass        = require('gulp-sass');

// Static Server + watching scss/html files
gulp.task('serve', ['sass'], function() {

    browserSync.init({
        server: "src/"
    });

    gulp.watch("scr/sass/*.sass", ['sass']);
    gulp.watch("scr/*.html").on('change', browserSync.reload);
});

// Compile sass into CSS & auto-inject into browsers
gulp.task('sass', function() {
    return gulp.src("scr/scss/*.scss")
        .pipe(sass())
        .pipe(gulp.dest("scr/css"))
        .pipe(browserSync.stream());
});

gulp.task('default', ['serve']);

____________________________________________________________
I heard that in version 4 of gulp there is a different syntax, but I could not master it, what needs to be changed to make it work???
in the package.json file the following info:

{
  "name": "project",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "test": "echo \"Error: no test specified\" && exit 1"
  },
  "author": "Artur",
  "license": "ISC",
  "devDependencies": {
    "browser-sync": "^2.26.3",
    "gulp": "^4.0.0",
    "gulp-sass": "^4.0.2"
  }
}

________________________________________________________________________
Here is the
PS D:\8 error itself. Frontend\project> gulp
assert.js:42
throw new errors.AssertionError({
^
AssertionError [ERR_ASSERTION]: Task function must be specified
at Gulp.set [as _setTask] (D:\8. Frontend\project\node_modules\undertaker\ lib\set-task.js:10:3)
at Gulp.task (D:\8.Frontend\project\node_modules\undertaker\lib\task.js:13:8)
at Object.(D:\8.Frontend \project\gulpfile.js:6:6)
at Module._compile (module.js:653:30)
at Object.Module._extensions..js (module.js:664:10)
at Module.load (module.js :566:32)
at tryModuleLoad(module.js:506:12)
at Function.Module._load (module.js:498:3)
at Module.require (module.js:597:17)
at require (internal/module.js:11:18)

Answer 1

var gulp = require('gulp');
var browserSync = require('browser-sync').create();
var sass = require('gulp-sass');

gulp.task('sass', function(done) {
    gulp.src("scr/scss/*.scss")
        .pipe(sass())
        .pipe(gulp.dest("scr/css"))
        .pipe(browserSync.stream());


    done();
});

gulp.task('serve', function(done) {

    browserSync.init({
        server: "src/"
    });

    gulp.watch("scr/sass/*.sass", gulp.series('sass'));
    gulp.watch("scr/*.html").on('change', () => {
      browserSync.reload();
      done();
    });
  

    done();
});

gulp.task('default', gulp.series('sass', 'serve'));

Answer 2

Such questions began to appear every day. The syntax has changed in Gulp 4. The parallel and series properties appeared, square brackets disappeared. The old hapfiles don't work. Everything is detailed here .