VDA 7.6 will not register with 7.1 broker after upgrade.

(Also could affect newer versions of the VDA, suchas VDA 7.9+)

Upgrade the DDC to XenDesktop 7.6, or downgrade the VDA to 7.1.

Problem Cause

1.  Registration fails because this is an 7.6 Virtual Desktop Agent (Arthur) using PVD, and it’s requesting Registration from a XenDesktop 7.1 Delivery Controller (Bruin):

• [7.6 VDA BrokerAgent] BrokerAgent.RegistrationManager.AttemptRegistration AttemptRegistrationWithMulipleDdcs AttemptRegistrationWithSingleDdc [7.1 DDC BrokerService] Broker.Registrar.Probe
• A condition within BrokerAgent’s AttemptRegistrationWithSingleDdc method checks to see whether PVD is in a Ready status. If not, a call to BrokerService’s Registrar.Probe is kicked off, using the DDC’s IRegistrar WCF Endpoint.
• The IRegistrar server is a 7.1 DDC (in this scenario). This version of BrokerService does not support Probe. As such, it responds to 7.6 DDC BrokerAgent Probe request with a Result of False.
• This drives AttemptRegistrationWithSingleDdc to fail the Registration request, close the Registrar connection, and log the following trace event:
  • RegistrationManagr.AttemptRegistrationWithSingleDdc: PVD CBP version is not 1.5 or later

2. This behavior is by design.

• Upgrade DDC to a newer version or keep VDA at same version as the DDC (7.1).
• For additional details see "Mixed VDA Support" begining with XA/XD version 7.6