Google indexing shows ‘Soft 404’ error on home page

We have a dynamic website built on Angular.js and node.js. The website’s home page is not getting indexed on Google and gets a ‘soft 404’ error. Although the website is working fine and most of the pages are getting indexed, we come across this problem in the home page indexing. We are using prerender.io for prerendering angular pages.
screenshot of error

Source: AngularJS