Microsoft"During the life of a LTSC release, you can upgrade your devices to the next or latest LTSC release free of charge using an in-place upgrade."
This is confusing. I just tried upgrading from 2016 LTSB to 2021 LTSC, and the upgrade resulted in lost activation status, and the key of 2016 LTSB was not accepted. So, clearly, you cannot upgrade to the latest LTSC release for free? I verified it two times - the key works when I do a clean install of Windows Enterprise 2016 LTSB from en_windows_10_enterprise_2016_ltsb_x64_dvd_9059483.iso and is not accepted after I install the upgrade of en-us_windows_10_enterprise_ltsc_2021_x64_dvd_d289cf96.iso. I was extra careful to pick the same Windows editions - both not IoT and not N, both 64 bit. Upgrade just doesn't work. Oh, Microsoft, why are you punishing us? Do we have to buy a new LTSC license every time we decide to upgrade to the feature pack that normal Windows 10 users get for free?
