During the Machine Catalog creation wizard or during dynamic VM provisioning in Citrix Cloud (Citrix DaaS), the task fails at the hypervisor validation, resource check, or master image preparation stage with the following error:

Error: RemoteHCLCommunicationException

Description: The Citrix Cloud Connector or Delivery Controller was unable to establish a secure communication channel with the hypervisor host or cloud provider API endpoint via the Hypervisor Communications Layer (HCL).

The RemoteHCLCommunicationException occurs when the Citrix Cloud Connector hosting services cannot validate SSL certificates, establish outbound connection sockets, or authenticate against the hypervisor API endpoint (e.g., VMware vCenter, Azure, AWS, GCP, Nutanix AHV, or Citrix Hypervisor). Common triggers include expired hosting connection credentials, untrusted SSL certificates, proxy/firewall blockages, or uncommunicative Cloud Connector hosting services.

To resolve the RemoteHCLCommunicationException during MCS provisioning, execute the following troubleshooting and configuration checks on your Citrix Cloud Connectors and hosting infrastructure:

1. Verify Hypervisor Connection & Authentication Credentials

1. Log into the Citrix Cloud Console and navigate to DaaS > Zone / Hosting Connections.

2. Locate the hosting connection associated with the failing Machine Catalog.

3. Click Test Connection to verify if Citrix Cloud can successfully reach the hypervisor endpoint.

4. If the credentials or service principal keys have changed (e.g., Azure Client Secret expired or vCenter account password changed), select Edit Connection and update the credentials.

2. Validate SSL/TLS Certificates on Cloud Connectors

If connecting to an on-premises hypervisor (such as VMware vCenter, Nutanix AHV, or Citrix Hypervisor):

1. Log into each Citrix Cloud Connector server in the relevant Resource Location.

2. Open a web browser on the Cloud Connector and navigate to the hypervisor API endpoint URL (e.g., https://<vcenter-fqdn>/sdk).

3. Ensure the SSL certificate is fully trusted and shows no browser certificate warnings:

   • If using a self-signed or internal CA certificate, ensure the complete Root and Intermediate CA chain is imported into the Trusted Root Certification Authorities store on all Cloud Connectors.

   • Verify that the FQDN used in the hosting connection matches the Subject Name / SAN on the hypervisor certificate.

3. Check Network Proxy, Firewall, and Port Requirements

1. Confirm that local firewalls or proxy devices are not blocking outbound HTTPS (Port 443) or hypervisor-specific ports between the Cloud Connector host and the target hypervisor API.

2. If your Cloud Connectors run through an outbound proxy server, verify that the proxy settings permit bypass for local hypervisor management traffic or that the proxy is configured under netsh winhttp.

4. Restart Citrix Hosting Agent Services on Cloud Connectors

1. Log into all Cloud Connector VMs in the Resource Location.

2. Open services.msc or an elevated PowerShell window.

3. Restart the Citrix High Availability Service and Citrix Remote Broker Provider services on each cloud connector one by one.

   PowerShell

    

   Restart-Service "CitrixHighAvailability"
   Restart-Service "CitrixRemoteBrokerProvider"
   

4. Re-run the Machine Catalog creation wizard in Citrix Cloud Web Studio.

When provisioning new virtual machines or creating a Machine Catalog in Citrix Cloud, the operation fails with a RemoteHCLCommunicationException error. This issue is caused by communication failures between the Cloud Connector and the target hypervisor/cloud infrastructure hosting plugin layer (Hypervisor Communications Layer - HCL).