Citrix Delivery Controllers and Director have been upgraded to 2402 CU3.

Citrix Director was installed on a dedicated server.

The issue started occurring after the upgrade.

During the Delivery Controller upgrade, the option to install the latest Monitor and Director version was selected.

The latest version of Director has not been installed.

• Monitor service version: 7.44.100.206 (2503)
• Director version: 7.41.3100.32 (2402 CU3)

Application event log shows the error:

• Source: Citrix Director Service
• Event ID: 2

An unexpected error occurred when accessing the data source 'Unknown error.' ('http://DDC_FQDN/Citrix/Monitor/OData/v3').

User: 'DOMAIN\USER'
Console operation: 'Searching Historical Alerts information'

Additional information:
'The property 'ScopeEntities' does not exist on type 'Citrix.Monitoring.Repository.Methods.NotificationSummary'. Make sure to only use property names that are defined by the type.'

Compatibility issue between an older version of Citrix Director and a newer version of Monitor service.

Upgrade Director to the same version as Monitor service (7.44.100.206 (2503)).

Independent Release of Director for LTSR:

https://docs.citrix.com/en-us/citrix-virtual-apps-desktops/2402-ltsr/director/install-and-configure/independent-release-of-director-for-ltsr.html