VMware VCF 9.x
VMware NSX 4.x
During NSX upgrade tasks, REPO_SYNC is briefly marked as FAILED to trigger resync between NSX Managers. This is intended behaviour in some versions of NSX. REPO_SYNC remediation is automatically triggered in the background and is expected to complete within a short time.
If VCF prechecks are re-run during that window, corresponding precheck failures may be encountered.
While the automatic remediation of REPO_SYNC is expected to only take a short time, the NSX UI / API may take longer to reflect the updated STABLE status.
This is a condition that may occur in a VMware NSX environment.
During upgrade of NSX Edge groups, VCF precheck shouldn't be rerun, unless there's a specific need for it and that REPO_SYNC is reported as STABLE in NSX UI.
Once upgrading from VCF 9.x to VCF 9.x (as opposed to NSX 4.x to VCF 9.x in this case), the upgrade should benefit from product improvements implemented in VCF 9.x
If REPO_SYNC actually takes a long time to complete, it is possible that the network performance between NSX Managers is to be inspected.