Just yesterday HTC committed to two full years of updates after release for new phones, but it looks like the company isn't keeping the updates to recent hardware. Last night Martin Fichter, one of HTC's US vice presidents, posted a link for a ROM Update Utility file ("RUU") for Sprint's HTC EVO 4G LTE to Twitter. The RUU updates the phone to Android 4.3 and Sense 5. If you've got an EVO 4G LTE phone and a Windows computer, you can flash it right now.
Are you on an Evo 4G LTE, and you want 4.3/Sense 5? You can sideload this ROM, but it will erase your data. http://t.co/tKdZZSqdo6
— Martin Fichter (@mfichter) February 19, 2014
HTC's proprietary RUU files are self-contained Windows executables that flash new firmware onto phones over USB. As Mr. Fichter notes, it will overwrite any current user data, including all apps and local files. But if you're an EVO 4G LTE user, you'll probably want to flash it anyway - during a recent Reddit AMA, an HTC representative said that this particular phone won't be getting an Android 4.3 update over the air because of its partition size limit. That's disappointing, but I've got to give props to HTC for making the RUU available to users who want it. This is the sort of power user process that's usually relegated to phone modder forums and the like.
The RUU file is a huge 826MB. If you've backed up your data and you're ready to flash, just download the file to a Windows PC, connect your phone, run the file, and follow the instructions.
Source: Martin Fichter Twitter