Unable to add/create vCenter Cloud Account on VRA: error "Unable to tunnel through proxy. Proxy returns "HTTP/1.1 503 Service unavailable"

Products

• VCF Operations/Automation (formerly VMware Aria Suite)

Issue/Introduction

• Unable to add the vCenter cloud account on Aria Automation getting an error : "Unable to tunnel through proxy. Proxy returns "HTTP/1.1 503 Service unavailable"
• The service account that connects the Aria Automation to the vCenter has the correct credentials and privileges. 
• The connection between the Aria Automation and the vCenter  telnet/curl fails to validate a connection over port 443.
  curl -v https://<FQDN_VRA>:443

Cause

• This can happen if the Aria Automation does not have connectivity to the vCenter and port 443 over HTTPS is not opened as per doc: Create a vCenter cloud account in Aria Automation

Resolution

• This is a firewall issue. The Aria Automation connects to the vCenter to add the cloud account over HTTPS on port 443 and needs to be opened for the cloud account to be added to the VRA.  Please ensure port 443 from Aria Automation to the vCenter is open and accessible, then add the cloud account.  

Additional Information

• Create a vCenter cloud account in Aria Automation