Can't Register Webhook For Twitter Account Activity Api [python3]

I'm trying to set up a Twitter app using the Account Activity API, to replace my old set up which used the user streaming endpoint. I want to be able to get DM messages to one user

Solution 1:

This turned out to be due to a combination of:

1. Not having created an environment here: https://developer.twitter.com/en/account/environments as described here: https://developer.twitter.com/en/docs/accounts-and-users/subscribe-account-activity/guides/getting-started-with-webhooks
2. using the wrong consumer secret in the function that created the token returned at the /webhook endpoint