The unattended Service Account Application ID is not specified or has an invalid value (SharePoint Server)
APPLIES TO: 
2013 2016 2019 Subscription Edition 
SharePoint in Microsoft 365
Rule name: The Unattended Service Account Application ID is not specified or has an invalid value.
Summary: The Unattended Service Account Application ID setting stores an application identifier (ID) in the registered Secure Store Service. The application ID is used to reference the Unattended Service Account credentials. The Unattended Service Account is a single, low-privileged account that Visio Graphics Service impersonates when it connects to data sources external to SharePoint Server, such as SQL Server. This account is required to connect to these external data sources. For more information about Visio Graphics Service, see Plan for Visio Services in SharePoint Server and Plan Visio Services security in SharePoint Server.
Resolution: Specify a valid application ID value
Verify that the user account that is performing this procedure is an administrator of the Visio Graphics Service service application and the Secure Store Service service application.
In Central Administration, on the Home page, in the Application Management section, click Manage service applications.
On the Service Applications page, click the Secure Store Service service application.
On the Secure Store Service page, record the application ID from the Target Application ID column.
For more information about the Secure Store Service service application, see Plan the Secure Store Service in SharePoint Server.
On the Service Applications page, click the Visio Graphics service application.
On the Manage the Visio Graphics Service page, click Global Settings.
On the Visio Graphics Service Settings page, in the External Data section, in the Unattended Service Account text box, type the application ID that you recorded in step 4 of this procedure.
Click OK.