"Task function must be specified at Gulp.set" error when running gulp

Question

I always have the same error when installing gulp:

C:\Users\Thomas\Desktop\Sites CT Graphics\colpaertmarc.be>gulp
assert.js:350
throw err;
^

AssertionError [ERR_ASSERTION]: Task function must be specified at Gulp.set [as _setTask] (C:\Users\Thomas\Desktop\Sites CT Graphics\colpaertmarc.be\node_modules\undertaker\lib\set-task.js:10:3) at Gulp.task (C:\Users\Thomas\Desktop\Sites CT Graphics\colpaertmarc.be\node_modules\undertaker\lib\task.js:13:8) at Object. (C:\Users\Thomas\Desktop\Sites CT Graphics\colpaertmarc.be\gulpfile.js:19:6) at Module._compile (internal/modules/cjs/loader.js:689:30) at Object.Module._extensions..js (internal/modules/cjs/loader.js:700:10) at Module.load (internal/modules/cjs/loader.js:599:32) at tryModuleLoad (internal/modules/cjs/loader.js:538:12) at Function.Module._load (internal/modules/cjs/loader.js:530:3) at Module.require (internal/modules/cjs/loader.js:637:17) at require (internal/modules/cjs/helpers.js:22:18)

Answer 1

This error occurs after you upgrade your gulp version from 3.* to 4.*. If you don't want to downgrade gulp, then you will have to rewrite gulp tasks to be valid with v4 api. Here is example how to rewrite simple gulp task from api notation used in v3 to notation compatiable with v4.

Gulp v3

var gulp = require('gulp');

// Deleting resources task
gulp.task('clearResources', function() {
  console.log('Deleting resources');
});

// Default gulp task
gulp.task('default', ['clearResources'], function() {
  console.log('Running default task');
});

Gulp v4

var gulp = require('gulp');

// Delete resources function
function clearResources() {
  console.log('Deleting resources');
};

// Gulp task(s)
exports.clear = clearResources;
exports.default = gulp.series(clearResources);