Oauth error invalid_request: The redirect_uri is not whitelisted

[bparanj]

I am getting invalid request error when I enter https://zephoinc.myshopify.com/ and click Install app button.

App setup has the ngrok setting:

Allowed redirection URL(s)
https://zephoinc.ngrok.io/auth/callback

ngrok output:

Session Status online
Account bparanj@zepho.com (Plan: Pro)
Version 2.3.40
Region United States (us)
Web Interface http://127.0.0.1:4040
Forwarding http://zephoinc.ngrok.io -> http://localhost:3000
Forwarding https://zephoinc.ngrok.io -> http://localhost:3000

error in log:

Processing by HomeController#index as HTML
Redirected to http://localhost:3000/login
Filter chain halted as :check_shop_domain rendered or redirected
Completed 302 Found

Appreciate any pointers on the cause of the problem. TIA.