unhandledpromiserejectionwarning: mongooseerror: the `uri` parameter to `openuri()` must be a string, got "undefined". code example
Example: unhandledpromiserejectionwarning: mongooseerror: the `uri` parameter to `openuri()` must be a string, got "undefined".
I think you miss importing env file.
require('dotenv').config({ path: 'ENV_FILENAME' });