What I'd call a potential Gotcha, updating/upgrading to Windows 10 2004 makes changes to the boot menu [BCD]. During the upgrade Windows has to restart -- to make sure that restart happens properly it changes the boot menu, later changing it back before setup finishes. In the past the restored boot menu was identical to the boot menu you had before the upgrade, though any customized names used by the menu, e.g. Windows 10 A or Windows 10 B, reverted to "Windows 10". Now however, upgrading to Win10 2004 causes the boot menu [BCD] to store more data.
This **might** cause problems in **some** cases. For most people the [I think small] risk is that the boot menu won't work & Windows won't start. Since I have more than one copy of Windows on this PC, I have the boot menu visible [every copy of Windows has a boot menu, but it's usually set to not display]. Renaming the upgraded copy of Win10 to something other than "Windows 10" in the boot menu failed using EasyBCD -- it might be that it couldn't handle the extra data, or it might have just failed that one time. I restored a backup that I'd made using EasyBCD before the upgrade and everything works fine.
I suggest that anyone upgrading to Win10 2004 should make sure that they backed up the boot files, either using a disk/partition image backup app and backing up the boot partition, &/or back up the boot menu using EasyBCD. It is possible that the changes to the boot menu files [BCD] will not happen when Win10 2004 hits general availability, and even with the changes the risk is low, but backing up those boot menu files is so trivial, takes so little time, that I think it's well worth the effort.
