ckeditor: Upload image not work in Rails 5

I created a blank project from scratch, add these gem:

gem 'mini_magick'
gem 'carrierwave'
gem 'ckeditor'

And follow any tutorial in README.

When trying to insert an image to a field, if I chose to upload from “image info” tab, image loading spinner just spins forever.

In the console, transaction immediately rollbacks without any error message.

If I chose to upload directly in “upload” tab, it returns this error:

Again, no transaction error messae in console