If you own a Sony Xperia device—or an older Sony Ericsson device—and are trying to mod it, flash a custom ROM, or unlock the bootloader, you have likely encountered a device in Device Manager listed as "S1Boot Fastboot" or "S1Boot Download Mode."
Without the correct driver, this device will sit under "Other Devices" with a yellow exclamation mark, preventing your computer from communicating with the phone. This guide covers what the driver is and how to install it. s1boot fastboot driver
Sony provides an official flash tool called "Emma." The driver bundle inside it is the most reliable. If you own a Sony Xperia device—or an
If the automatic installers fail, do it manually. If the automatic installers fail, do it manually
There are three primary ways to install this driver. Do not skip the prerequisites.
Issue: Device Manager shows "S1Boot Fastboot" correctly, but fastboot devices returns nothing.
Solution: This is often a USB 3.0 vs. USB 2.0 port issue. S1Boot protocol is notoriously picky. Plug your Xperia into a USB 2.0 port (usually black plastic inside, not blue). If using a laptop, use a powered USB hub.