Gulp: did you forget to signal async completion? Did you forget to signal async completion is a very common error for Gulp 4 users. Before Gulp 4, when we used Gulp 3.9.1 etc, everything works fine. We updated to version 4 and now what? Well, Gulp changed a lot and we need to update our gulp files. Let’s see one: gulp.task('styles', function () { return gulp.src(['./parent-style.css', './style.css', './scss/*.scss']) .pipe(autoprefixer()) .pipe(sass({outputStyle: 'compressed'}).on('error', sass.logError)) .pipe(concat('style.min.css')) .pipe(gulp.dest('.')); }); This is one task from one of my projects. It runs smoothly with Gulp 3.9.1. But when I upgraded to Gulp 4, I got this did you forget to signal async completion error while running…