rails 6 nginx passenger setup webpacker

Question

I am trying to deploy rails app with nginx & passenger. I have set up everything. Now when I try to run my application, I get following error in production,

ActionView::Template::Error (Webpacker can't find application in /var/www/rails/bridge_plus_app/public/packs/manifest.json. Possible causes:
App 46665 output: 1. You want to set webpacker.yml value of compile to true for your environment
App 46665 output:    unless you are using the `webpack -w` or the webpack-dev-server.
App 46665 output: 2. webpack has not yet re-run to reflect updates.
App 46665 output: 3. You have misconfigured Webpacker's config/webpacker.yml file.
App 46665 output: 4. Your webpack configuration is not creating a manifest.
App 46665 output: Your manifest contains:
App 46665 output: {
App 46665 output: }
App 46665 output: ):

there is no file(manifest.json) in my /public directory