"The source machine hostname '###.###.###.###' resolves to IPv6 address(es) ';; communications error to <DNS server IP address>#53: timed out, ;; ..." while upgrading VCSA 7.0 -> 8.0 fails at Stage 2 Pre-check

Products

• VMware vCenter Server

Issue/Introduction

While upgrading a vCenter Server Appliance (VCSA) from 7.0 to 8.0, the upgrade process fails at Stage 2 -> Pre-Checks due to an IPv6 resolution issue.

Symptoms:

• Upgrade is stuck at Stage 2 → Pre-Checks.
• vCenter Server is deployed using an IP address as PNID (Primary Network Identifier).
• IPv6 is disabled on vCenter Server.
• Error observed during Pre-Checks (Phase 2) when the source vCenter Server IP is ###.###.###.###.

Error: 

The source machine hostname '###.###.###.###' resolves to IPv6 address(es) ';; communications error to <DNS server IP address>#53: timed out, ;; communications error to <DNS server IP address>#53: timed out', but IPv6 networking will not be preserved after the upgrade. This will prevent certain services preferring IPv6 from establishing network communication.

Resolution

Either remove the DNS IPv6 entry for hostname '###.###.###.###' or change the network configuration of the source machine to pure IPv6, or in case a dual networking stack is needed, set a static IPv6 address.

Environment

VMware vCenter Server Appliance 7.0.x

VMware vCenter Server Appliance 8.0.x

Cause

The upgrade scripts verify whether the source vCenter Server PNID resolves to an IPv6 address.
If a DNS server does not return a prompt answer against an IPv6 address resolution query, the query got a timed out error and Stage 2 pre-checks fail. 

Resolution

From the error message, the supported resolutions are:

• Option 1: Configure the DNS server to respond promptly against IPv6 address resolution query. 
• Option 2: Change the PNID from IP address to FQDN. 

Additional Information

Reconfigure the Primary Network Identifier