Resolved
This issue has been resolved.
Monitoring
All Heroku services have been restored, we are monitoring for any further issues.
Update
It is now possible for all accounts to log into Heroku. Heroku External Objects for Connect users are recovering though may still be intermittent.
Update
Heroku logins, including access to third-party add-ons, with the exception of accounts that have Multi-Factor Authentication in use have been restored.
Update
All Heroku dashboard and CLI logins, including logins to third party add-ons via the Heroku dashboard or CLI, are currently unavailable.
Issue
We are receiving reports of services backed by Salesforce being unavailable due to ongoing DNS issues. This includes