Error: "Operation aborted due to an unexpected error" when selecting to view more than 20 vApp when creating a new replication

Products

• VMware Cloud Director

Issue/Introduction

• You try to create a new incoming replication and when selecting to view more than 20 vApp or VM on the page you get the error below:
  
  Operation aborted due to an unexpected error


• On the destination VMware Cloud Director Availability (VCDA) site in  /opt/vmware/h4/cloud/log/cloud.log you have an entry similar the one below:

  DATE TIME ERROR - [UI-########-####-####-########55-cF] [https-jsse-nio-8443-exec-4336] c.v.h.c.c.error.ExceptionAdvisorBase     : A GET request from [email protected][##.##.##.##] to /inventory/vapps?sort=&offset=0&limit=50&site=cloud.example.com&orgId=-########-####-####-########977e failed.com.vmware.vcloud.client.exception.JAXBFault: javax.xml.bind.UnmarshalException: unexpected element (uri:"", local:"html"). Expected elements are <{http://www.vmware.com/vcloud/extension/v1.5}AclRule>,<{http://www.vmware.com/vcloud/v1.5}AclRuleRecord>,<{http://www.vmware.com/vcloud/v1.5}AclRuleReference>,<{http://www.vmware.com/vcloud/v1.5}AclRuleReferences>,[...]

• You have a Load Balancer (LB) on top of the VMware Cloud Director VCD cells.

Environment

VMware Cloud Director 10.6

VMware Cloud Director Availability 4.7.3

Cause

VCDA made the GET request and instead of receiving an XML response, the received response an HTML from the LB.
this usually happens when the HTTPS request header size and/or response header size and/or the response timeout are not correctly configured or if there is a low rate limit configured on the LB or any other misconfiguration.

Resolution

Review and adjust the LB configuration according to the documentation VMware Cloud Director Cell Load Balancing Configuration.
Increase the LB rate limit.