vCenter Server Upgrade Failed at Stage 2 with Error: "Pre-upgrade check failed due the following problem: Error in method invocation [Errno 1] Unknown host"

Products

• VMware vCenter Server

Issue/Introduction

Upgrading vCenter Server failed with following error:

Pre-upgrade check failed due the following problem: Error in method invocation [Errno 1] Unknown host

The ESXi host managing the source vCenter Server is specified by its IP address.

The file /var/log/vmware/applmgmt/applmgmt.log on the destination vCenter Server shows the following logs:

YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.spec_validators:Validating source_location: <Source ESXi IP>
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.network_utils:Testing connection to <Source ESXi IP>:443.
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.network_utils:Connection test to '<Source ESXi IP>:443' was successful.
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.spec_validators:Checking source_location SSL certificate: <Source ESXi IP>
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.spec_validators:No verification is performed.
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.network_utils:Address '<Source ESXi FQDN>' is not an IPv4 address.
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.network_utils:Address '<Source ESXi FQDN>' is not an IPv6 address.
YYYY-mm-ddTHH:MM:SS AM UTC [9566]INFO:vcenter.network_utils:Returning IPs set() and FQDNs {'<Source ESXi FQDN>'}.
YYYY-mm-ddTHH:MM:SS AM UTC [9566]DEBUG:cis.filelock:Releasing lock /etc/vmware/deploy/lifecycle.global.mutex.upgradeLock
YYYY-mm-ddTHH:MM:SS AM UTC [9566]ERROR:vmware.vapi.provider.local:Error in invoking com.vmware.vcenter.deployment.upgrade in check - [Errno 1] Unknown host
Traceback (most recent call last):
  File "/usr/lib/applmgmt/vapi/lib/vapi_runtime-2.100.0-py2.py3-none-any.whl/vmware/vapi/provider/local.py", line 277, in invoke
    method_result = self._invoke_int(
  File "/usr/lib/applmgmt/vapi/lib/vapi_runtime-2.100.0-py2.py3-none-any.whl/vmware/vapi/provider/local.py", line 249, in _invoke_int
    method_result = iface.invoke(ctx, method_id, input_value)
  File "/usr/lib/applmgmt/vapi/lib/vapi_runtime-2.100.0-py2.py3-none-any.whl/vmware/vapi/bindings/skeleton.py", line 371, in invoke
    meth_output = method(**meth_args)
  File "/usr/lib/applmgmt/vcenter/py/vmware/vcenter/deployment_impl.py", line 336, in check
    return validator.validate(spec, dt.get_type())
  File "/usr/lib/applmgmt/vcenter/py/vmware/vcenter/spec_validators.py", line 1894, in validate
    self._validate_source_container(spec)
  File "/usr/lib/applmgmt/vcenter/py/vmware/vcenter/spec_validators.py", line 1779, in _validate_source_container
    self.validate_ssl(con.hostname, con.username, con.password,
  File "/usr/lib/applmgmt/vcenter/py/vmware/vcenter/spec_validators.py", line 891, in validate_ssl
    is_host_valid, emsg = self.net_utils.validate_address_with_ssl_cert(
  File "/usr/lib/applmgmt/vcenter/py/vmware/vcenter/network_utils.py", line 400, in validate_address_with_ssl_cert
    if NetworkUtils.validate_reverse_lookup_fqdn(address, cert_fqdns):
  File "/usr/lib/applmgmt/vcenter/py/vmware/vcenter/network_utils.py", line 357, in validate_reverse_lookup_fqdn
    hostnames = socket.gethostbyaddr(address)
socket.herror: [Errno 1] Unknown host

Cause

This issue occurs when the reverse DNS lookup of the ESXi IP address that manages the source vCenter Server fails.

Resolution

Add a PTR record for the ESXi host to the DNS server, then retry Stage 2.

Additional Information

If the issue persists after adding the PTR record, try clearing the DNS cache on the vCenter Server by running:

systemctl restart dnsmasq