Upgrade handlebars.js to version 4.7.3

My goal is to upgrade handlebars from version 1.1.2. to 4.7.3. I have downloaded version 4.7.3. and added it to index.html. I also changed handlebars version in package.json file and run npm install handlebars -g. But when I try to open the application everything crashes, I get this error: "Unknown template object: function". I debugged this issue and figured out that templateSpec.main is undefined. I am new to this, so I would be grateful if someone can provide me detailed answer how to fix this issue. I found already similar topic, but I didn't understand what to do if the problem is in precompiling. P.S. The application is in old Ember version 1.7.1. (I am not allowed to change Ember version btw).