/common/logs/admin/web.log
<timestamps> UTC [https-jsse-nio-127.0.0.1-8443-exec-9, Ent: HybridityAdmin, , TxId: TxId: ####-####-####] INFO c.v.h.i.util.InterconnectFeatureUtil- Executing validator Feature Validator, Validation request: {"featureId":"l2ha","sourceEndPoint":"systemId-####-####-####","destinationEndPoint":"systemId-####-####-####","validateHybridityManager":true,"hybridityManagerVersion":"4.3.0"}
Go to HCX hybridity 443 UI > Support and confirm the HCX Manager version
Example below :

HCX hybridity 443 UI > Interconnect > [Choose the Service Mesh] > VIEW APPLIANCES > [Confirm the IX/NE version]VMware HCX 4.3 or later
The value "hybridityManagerVersion":"4.3.0" represents the minimum manager version required for Network Extension (NE) to support High Availability (HA).