V2T Host migration to NSX-T version earlier than 3.2.1 fails with "error_code" : 30491 when host was onboarded after configuration was imported

Products

• VMware NSX

Issue/Introduction

Symptoms:
- NSX V2T migration is to NSX-T version earlier than 3.2.1
- At least one ESXi host was added to an NSX-V cluster being migrated to NSX-T after the Import Configuration phase of the migration
- Host migration is failing with error:
Execution of v2t script failed for host <UUID>:host-XXXXXXX [[UC] Error in rest call. url= upgrade-mgmt/ucmessage/<UUID>?action=send_msgs , method= POST , response= { "httpStatus" : "INTERNAL_SERVER_ERROR", "error_code" : 30491, "module_name" : "upgrade-management", "error_message" : "Some error has occurred." } , error= 500 : [{ "httpStatus" : "INTERNAL_SERVER_ERROR", "error_code" : 30491, "module_name" : "upgrade-management", "error_message" : "Some error has occurred."
 
/var/log/migration-coordinator/v2t/cm.log on NSX-T Manager shows the following logging:
<timestamp> CM.plugins.l2_utils WARNING  Couldn't find tn spec of host host-XXXXXXX in file /var/log/migration-coordinator/v2t/host-tn-config.json
<timestamp> CM.plugins.l2_utils WARNING  Couldn't find tn spec of host host-XXXXXXX in file /var/log/migration-coordinator/v2t/host-tn-config.json

Cause

This behavior is expected if a host is onboarded after the migration is started, and the host-tn-config.json file is compiled when migrating to NSX-T versions before 3.2.1.

Resolution

Support for adding hosts after the NSX-V configuration is imported to the NSX-T Migration Coordinator was introduced in NSX-T 3.2.1.

Workaround:
If migrating to an NSX-T version earlier than 3.2.1, hosts can be prepared for NSX-T by uninstalling NSX-V VIBs and installing NSX-T VIBs outside of Migration Coordinator. Once T VIBs are installed on a host via the NSX-T UI, Migration Coordinator will recognize the host already is prepared for NSX-T when the migration is next resumed.