Migrate interfaces: Failed to update, system.interface must be handled manually

[peter-supply]

We are migrating to Fortiswitches.  Currently, we use third party switches (HPE).  We have 200F Fortigates in an HA pair.  We are have a Fortiswitch 1048E switch connected to the Fortigate.  We need to migrate the VLANs on a Fortigate "LAN port"  to the Fortiswitch.  We are using this KB: https://community.fortinet.com/t5/FortiGate/Technical-Tip-Migrating-VLAN-interfaces-from-one-interfa....  When we migrate the Fortigate LAN interface and all VLANs to the Fortilink, we receive a message "Failed to update.  An error occurred when attempting to change this reference (system.interface), this reference must be handled manually."  The migration completely fails.  How can we successfully migrate VLANs from the Fortigate to the Fortilink port?

[AEK]

On FGT CLI, type "show system interface" and tell us if the related FortiLink is defined before or after the VLANs you want to migrate.

[peter-supply]

We need to migrate the VLANs on x3 (which is currently a "LAN interface") to Fortilink.  After running "show system interface," I see x3 defined in the results BEFORE the "fortlink" interface.

[peter-supply]

Our Fortigate 200F is in a HA pair and the HA is on 7.2.11.  We just installed the 1048E switch- the switch is on 7.6.1.

[peter-supply]

And to clarify, the interface (x3) that has the VLANs is BEFORE the "Fortlink" interface.  But the VLANs themselves are AFTER the Fortilink interface.

[AEK]

If the VLANs are after the FortiLink then that's fine.

Can you share a screenshot of failed changes on the migration wizard?

[peter-supply]

I obscured the names of the objects- this is just a sample of the errors.