The "top of the heap" for BB10 OS builds, including critical security patches like KRACK and Broadcom fixes, along with a webkit engine upgrade. Maintenance & Flashing Tools
Even with the correct BlackBerry Z30 firmware, problems can arise. Here is how to fix them: Blackberry Z30 Firmware
There are two main final "branches" of firmware for the Z30. The "top of the heap" for BB10 OS
Always download firmware for your exact STA100 model. A -3 autoloader on a -1 will lose LTE. Blackberry Z30 Firmware