HTC has rolled out July security update for the unlocked variant of HTC 10. The catch is that the update is currently available only in the USA. After the installation, the unlocked HTC 10 model will be updated with several bug fixes in addition to improvements.
With build number 2.51.617.1, the July security update for unlocked HTC 10 smartphone measures 636.15MB in size. Hence, the activation of Wi-Fi is very much required to install the update. The official dashboard page states that the update includes improvements, bug fixes including system related enhancements.
When compared to previous releases, the total capacity of the update is higher for a security update. That said, if you have a 4G connectivity with over 1GB daily bandwidth limit, then it is possible to install the update over mobile data.
Moreover, the update page clearly states that the data will not be deleted after the installation. It also directs to the homepage of the HTC if you have any questions regarding the update.
HTC has released the update via OTA. Hence, it will take few days for the update to become available on your smartphone. If the update message notification is not visible, then it is possible to manually check the presence of the update by tapping Settings icon. It is also possible to postpone the update installation by selecting Later button from the system update page.