Impacts of disconnecting and reconnecting Marketing cloud to same or a different Sales/Service org

Changing the Salesforce System User or disconnecting and reconnecting to the same or a different Agentforce Sales (formerly Sales Cloud) or Agentforce Service (formerly Service Cloud) org will have an impact on your Marketing Cloud Connect implementation. To change the Salesforce System User you will have to disconnect and reconnect. Please use this article if you are trying to change the Marketing cloud API user.

How to find details of Salesforce System User?
Go to Marketing Cloud> Setup> Apps> Salesforce Integration.

How to find the MC API user?
Login using Salesforce System User> App Launcher> Marketing Cloud? Marketing Cloud Connect Settings

Impacts of Disconnecting:

Please check this article for more information on disconnect impact. Other impacts that could be experienced include:

1. You will have to set up the Synchronized Data sources again.
2. Any Automations that depend on Synchronized Data Extensions will also have to be stopped/paused.
3. You will have to create a new version of Journeys that use Salesforce Entry events and Salesforce activities.
4. Individual Email results will be lost while the two products stay disconnected.

Post Reconnection Impact:

1. Please use this article to reconnect.
2. You will have to set up the Synchronized Data Sources and the fields linked to those sources again.
3. When you reconnect, the Synchronized Data Extension names may be different so you may have to change the automations/SQL activity that depended on the historic Synchronized Data extensions Names.
4. You will have to create a new version of the Journey for every existing Journey that has a Salesforce Entry even or a Salesforce activity that updates data on Sales/Service.
5. If you are reconnecting to a different Org, Individual Email results for historical Journeys will fail to sync.