Rails 5: Sprockets::FileNotFound - couldn't find file 'jquery-ui/autocomplete' with type 'application/javascript'

change the line in application.js

from

//= require jquery-ui/autocomplete

to

 //= require jquery-ui/widgets/autocomplete

Seems the file paths have changed. According to the gem readme:

Warning:

Due to directory structure changes between jQuery UI 1.10, 1.11, and 1.12, if you use version is lower than 6.0, you will have to use a different naming for the files to require, please check following links for more information: for 5.0 users, for 4.2 users.