: Officially known as "Windows 8.1 Update (KB2919355)," Update 3 is a mandatory rollup released in April 2014. It is a prerequisite for virtually all security updates released after 2014. Without Update 3, your system is unable to receive further patches and many modern applications (like newer browsers or drivers) will refuse to install. Having it integrated means you don't need to install it after setup.
Given that the AIO ISO exceeds 4GB, you cannot simply copy it to a FAT32 USB drive because of file size limitations. Here’s the correct method: FULL Windows 8.1 AIO Update 3 x86 x64 pt-BR