I'd take Timo's advice, cause you are not telling us the UCSM version you are running, nor drivers currently used and other necessary details.
To add something, check Cisco's Release notes based on the UCSM version you are running and the ESXi version you want to update to. It is not only a matter of seeing if it is supported, it is also something about knowing your environment and how it will behave later on, after the upgrade.
Introduction This article will help you understand the steps on how to
download the UCS licenses from the Cisco Systems website and then
installing it on the UCS. The redacted (blue lines) just covers up
certain numbers for privacy please do not take them...
Introduction This article will help you understand and educate the
customer on how to clear their "expired licenses"
(license-graceperiod-expired) from their UCS-M. If a customer just
purchased a license and needs a step by step guide on how to download
Introduction Prepositioning is a powerful tools on the WAAS platform but
it is not always easy to figure out why your jobs are failing when
trying to retrieve the files.Here is a method that should help you to
figure out the reason why they are not succes...