Article number
Affected Versions
Source Hypervisor
Target Hypervisor

Error: “The remote server returned an error: (503) Server Unavailable” when Installing a VRA

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An administrator may find a VRA install fails due to a 503 - Server Unavailable error.

Root Cause

When checking for all VPX settings in advanced system settings in vCenter, these two items are missing:



The following error is seen when a VRA install fails:

VRA installation Failed: error while inserting C:\Program Files\Zerto\Zerto Virtual Replication\vra\vra-disk1.vmdk into vm. Exception System.Net.WebException: The remote server returned an error: (503) Server Unavailable.


To workaround this issue, follow the below steps:

  1. Try deploying the VRA OVF manually on the same host by using the OVF file on the ZVM. This will likely fail with a similar error to the below:
    1. Transfer failed: Error transferring file to https://*/nfc/525e6041-62ab-9a80-69ae-2be506115584/disk-0.vmdk: *: Name or service not known
  2. If the manual deployment fails on the host, VMware Support should be engaged for further assistance with fixing the /etc/vmware/vpx/vpxa.cfg file on the host.
    1. The missing settings can be found by comparing a vpxa.cfg file of a host that can deploy an OVF template successfully or has a healthy VRA installed already with the unsuccessful host.
  3. If the manual deployment is successful on the host, engage Zerto Support for further troubleshooting.