After your CRM instance is updated to a different major version, CRM for Outlook is disabled and appears grayed out. If you attempt to access one of the CRM folders, you encounter the following error message:
"You are running a version of Microsoft Dynamics CRM for Outlook that is incompatible with this Microsoft Dynamics CRM organization (<version number>)."
This can occur if your CRM for Outlook version is not compatible with the updated version of your CRM instance. CRM for Outlook is only compatible with a CRM instance that is the same major version or 1 major version higher. For example: CRM 2013 for Outlook is compatible with a CRM 2013 or CRM 2015 instance. If your CRM instance is updated to CRM 2016, CRM 2013 for Outlook would not be compatible. You would need CRM 2015 for Outlook or CRM 2016 for Outlook (recommended).
CRM 2013 = version 6.x
CRM 2015 = version 7.x
CRM 2016 = version 8.x
Upgrade CRM for Outlook to be the same major version of your CRM instance or a maximum of 1 major version lower. If you are using CRM 2013 for Outlook and want to upgrade to CRM 2016 for Outlook, you either need to first upgrade to CRM 2015 for Outlook or uninstall CRM 2013 for Outlook prior to installing CRM 2016 for Outlook.
If you encounter an error trying to install or uninstall CRM for Outlook, run the Program Install and Uninstall troubleshooter.
If you still encounter issues installing, enabling, or connecting CRM for Outlook with a CRM Online organization, run the Microsoft Support and Recovery Assistant.