"Error registering: Provider OAuth refresh token is empty. Maybe previous token wasn't properly revoked!"
To have a secured connection between InboxZero and your mailbox which is stored at your provider, your provider will provide an authorisation token to us to access your emails.
At certain time intervals this token will be updated to keep a secured connection. In some cases it may occur, following a technical error, that your old token is blocking the creation of a new one.