Thanks! That's exactly the error message I'm getting. It doesn't matter if it's my Windows 10 setup or Ubuntu 14.04. I have tried both /dev/ttyUSB0 and /dev/ttyUSB1 on Linux and on Windows, I just look at Device Manager and use make menuconfig to change to the appropriate serial port.

We purchased an ESP-WROVER-KIT and installed Eclipse and command-line development environments on both Windows and Linux (Ubuntu 14.04 LTS). After following all instructions, we are unable to download binaries in either environment, with exactly the same message: Connecting ....._____....._____ and ...