failed assignments" and "Licenses could not be assigned to the selected vCenter".This license could not be assigned to the selected vCenter system. Check the network connection between the license server and the selected vCenter system and try again.

Licenses could not be synchronized with vCenters.” or “Add-on licenses could not be synchronized with vCenters.”/storage/log/vcops/log/collector.log on VCF Operations may show the following error:com.vmware.adapter3.vmwareinfrahealth.helpers.vcenter.collector.VCenterAvailabilityMetricsCollector.addNTPServerAndDriftMetric] [NTP DRIFT] NTP drift is not performed cause this setup vCenter-<vCenterFQDN> as its vROPs is not configured with NTP server.This issue occurs due to network connectivity failures or time drift disrupting communication between VCF Operations, the vCenter Server, and the license server.
Alternatively, this issue occurs when a vCenter Server instance upgraded from version 5.x retains an uppercase instanceUuid (vcGuid) inside the configuration files /etc/vmware-vpx/instance.cfg and /etc/vmware-vpx/firstboot/vpxd-service-spec.prop. Uppercase identifiers prevent successful authentication requests to the license server.
Follow the sections below to verify connectivity, synchronize time, and resolve configuration blocks across the environment.
Time drift exceeding 30 seconds between the license server, vCenter Server, and VCF Operations causes authentication and synchronization failures.
Open SSH sessions to the ESXi host running the license server, the vCenter Server, and the VCF Operations appliance.
Run the following command in quick succession on each component to check the current UTC time:
date -u +"%Y-%m-%dT%H:%M:%SZ"
If timestamps differ by more than 30 seconds, configure an identical NTP server across all components:
Check the status of current license assignments:
Access the vCenter Server appliance via SSH.
Validate TCP port 443 connectivity to the license server by running:
curl -v -k https://<license-server-IP>
Alternatively, run:openssl s_client -connect <license-server-IP>:443
If the connection fails or blocks, add an explicit firewall rule to allow TCP port 443 traffic from the vCenter Server IP address to the license server IP address.
Verify the vApp network settings if the license server IP address or gateway requires correction. In the vSphere Client, power off the license server VM, navigate to Configure > vApp Options, update the fields, and power on the VM.
Test forward and reverse DNS resolution from the vCenter Server using nslookup:
nslookup <license-server-hostname> <vCenter-DNS-IP>nslookup <license-server-IPAddress> <vCenter-DNS-IP>
To identify the vCenter Server DNS IP address: Log in to the vCenter Server Appliance Management Interface (VAMI) at https://<vcenter_IP_or_FQDN>:5480. Navigate to Networking, and under Networking Settings, click Edit > Next, then expand Hostname and DNS to locate the configured DNS server entries.
To identify the license server hostname and IP address: Locate the license server VM in the vCenter Inventory, launch the Remote Console, and retrieve the values listed under Hostname and IP Address.
If the lookups fail, create an A record for the license server hostname in the primary DNS server utilized by vCenter Server.
In VCF Operations, navigate to Manage > Licensing > Licenses & Registration.
Under Registration and License Server Status, click Manage > License Servers to inspect the Connectivity to VCF Operations column.
If the status shows Not Connected or if the server does not appear after enrollment, open an SSH session to a host on the same management subnet as the license server and test port 443 access to VCF Operations:
curl -v -k https://<VCF-Operations-IP>
If blocked, configure an allow rule on the network firewall for TCP port 443 from the license server subnet to the VCF Operations IP address.
Verify DNS resolution for the VCF Operations FQDN from the license server's designated DNS server:
nslookup <VCF-Operations-hostname> <license-server-DNS-IP>
If the returned IP address is incorrect or returns NXDOMAIN, update the A record in the DNS server, or correct the vApp DNS options by powering off the license server VM and adjusting Configure > vApp Options > Domain Name Servers.
In VCF Operations, navigate to Operate > Inventory, select the specific vCenter targeted for license assignment, and select the Alerts tab.
Verify if an alert reading Connectivity to the vCenter is affected is present, confirming an active communication block via the user interface.
Access the VCF Operations appliance via SSH.
Test TCP port 443 outbound access to the vCenter Server by running: curl -v -k https://<vCenter-IP>
If blocked, create a network firewall rule allowing TCP port 443 from the VCF Operations IP address to the vCenter Server IP address.
Verify hostname resolution using nslookup: nslookup <vCenter-hostname> <VCF-Operations-DNS-IP>
If resolution fails, add the appropriate A record to the DNS server configured on the VCF Operations instance.
Launch the vCenter Server appliance shell via SSH.
Check the casing of the unique identifier by running:
grep instanceUuid /etc/vmware-vpx/instance.cfg
Example output:instanceUuid=DBE#####-1##B-##BC-CA##-##CDC#####
If the instanceUuid contains uppercase letters, convert the identifier to lowercase. For detailed steps, see the resolution section of KB - Registering VASA provider fails with error "A problem was encountered while registering the provider"
In VCF Operations, navigate to Operate > Dashboards > All > License Server Health.
Select the target license server to review CPU, memory, and disk utilization.
If CPU or memory utilization permanently exceeds 90%, reboot the appliance from the vSphere Client by navigating to the VM and selecting Actions > Power > Reset.
If a disk partition (root or data disk) is full, expand the virtual hardware storage allocation:
Connectivity diagram between License Server and other components: