Heroku

### App
Heroku

### Summary:
Heroku connected account went unhealthy; reconnecting fails with Heroku error "Couldn't find that registered client" - appears to be an issue with Pipedream's built-in Heroku OAuth client, same as issue #21805.

### Details:
Our existing Heroku connected account was flagged unhealthy (we received the automated notification email on 8/28/26).

When we attempt to reconnect from the Connected Accounts page, the Heroku OAuth popup shows "Couldn't find that registered client" before any authorization screen appears. Logging into Heroku inside the popup just lands on the Heroku dashboard — the OAuth callback never completes, and the account stays unhealthy.

We have no custom OAuth clients in this workspace, so the connection uses Pipedream's built-in Heroku OAuth client. The Heroku error indicates that client ID is no longer registered on Heroku's side, which we can't fix from our end.

This looks identical to #21805 (opened Aug 27, 2026) and to #6025 from 2023, which was resolved on Pipedream's side.

Several production workflows depend on this connection (CMS webhook → Heroku deploy), so deploys are currently broken for us.

### Screenshots:


Start by reproducing the failure from the Connected Accounts page and compare the behavior with issues #21805 and #6025. Inspect the built-in Heroku OAuth client configuration and the Heroku OAuth popup flow; done means the callback completes and the existing connected account is healthy again.

Written by the indexing model from the issue text.