I just found the reason for this. Hubspot automatically checked off 14 new access scopes under the CRM tab. My old install link had the ‘contacts’ scope and two others. There is no ‘contacts’ scope any more. I removed ‘contacts’ from the link since it was not actually being used and unchecked all the CRM scopes, and now the app works again. If the same thing happened to you and you were using the ‘contacts’ scope for something, you probably need to update the URL with the 14 new CRM scopes that replaced it.