Q:

how can i solve this error 'The following tasks did not complete: default, Did you forget to signal async completion? '

this is my gulpfile.js
const gulp = require('gulp');
gulp.task('default', function () {
});

I write gulp in my terminal
and response is..
[19:47:02] Using gulpfile D:\DEV64\LearningJS\gulpfile.js

[19:47:02] Starting 'default'...

[19:47:02] The following tasks did not complete: default

[19:47:02] Did you forget to signal async completion?

what can i do?

A:

In Gulp 3.x you didn't need to signal completion. But from Gulp 4.x you need to do that.
Gulp automatically passes a callback function to your task as its first argument. Simple way in your case would be calling the callback. 
gulp.task('default', function(done) {
  console.log("Started");
  done();
});

For more information You can check this question out: Gulp error: The following tasks did not complete: Did you forget to signal async completion?

A:

This works nicely for me.
gulp.task('default', async  function(){
  console.log("This is default task!");
});

You can also try this one.
gulp.task('default', async ()=>
 console.log('This is default task!')
);

