Preparing for upgrades, you find you have some workload that should not be moved.
You recieve the following error in the prechecks:
“Host needs to be placed in vSphere Maintenance Mode before upgrade.”
Vsphere 7.x, 8.x
NSX T
NSX 4.2.x
NSX 9.x
A prerequisite for doing an upgrade to NSX is to put the ESXi host in Maintenance Mode.
There is an "In Place Upgrade" option, however there are a lot of caveats. See VMware NSX Upgrade Guide.