Rooting a device can bring a wealth of features and functionality to a user's device. In truth, the act of rooting does not add anything in itself, but what it does do is offer access to the device at a level where the functionality can then be achieved. While some devices are easier to root, others are not so easy. As such, the ability to root a newer device is largely dependent on how easy it is to begin with and how much people want the device to be rooted. One of those devices which had proved difficulty in gaining root access was the Sony Xperia Z3.
In fact, it was becoming so difficult that back in November a now-common bounty began for the device. For those unfamiliar with root bounties, these are usually where the community comes together and offers a collective bounty, which is awarded to whoever can find an exploit and gain root privileges. As such, November saw the announcement of the start of the bounty for much of the Xperia Z3 line of devices. The good news came by January when root seemed to be achieved for the Xperia Z3 using a method developed by XDA member zxz0O0. That said, the method did not seem to work so well for the T-Mobile version of the Xperia Z3. This was due a locked bootloader and a patch for the exploit already included in the specific carrier variant's firmware.
As such, by February a bounty began specifically designed for the T-Mobile Xperia Z3 (model number D6616). Well, root seems to now have also been achieved for the D6616. Again, the exploit which gains the root privileges was determined by zxz0O0 and working off the more general Z3 exploit. For those interested in gaining root access on the T-Mobile version, the feedback so far from those testing the method is slightly mixed. This seems to be due to issues when trying to install. Therefore, if the current and main method (source link below) does not work then you are advised to read on from the method post as the thread does go to further collectively explain how to gain root access. If you are running a Verizon version of the Sony Xperia Z3, then it seems this exploit also works for your device too. Click the source link below to find out more.