As mentioned at the start of this update guide, Fonteva is aligning with Salesforce’s security requirements, including Sharing. When enabled, Sharing can sometimes restrict the visibility of records, so Sharing Sets are used to allow administrators to give access to records in the system to Contacts in the database.
If Sharing Sets are not configured after updating to Fonteva 20Spring.1, your users will be unable to successfully utilize parts of your Community Portal as they did pre-upgrade. They will be missing access to records they would have had access to prior to updating. This makes it vital for you to configure Sharing Sets. Follow the directions in the Sharing Sets section in System Documentation to successfully configure Sharing Sets for your org.
When you have successfully configured Sharing Sets for your org, please move forward to Reactivate Customizations.