I also have the same problem on m5stickC and m5stickC plus today. Everything was working fine two days ago when I last used it, and I did not change anything (same firmware 1.7.8, etc), but it just does not connect. I also tried changing the server between China and Singapore, but it did not make a difference. Any help would be greatly appreciated.

Thanks very much! A simple workaround me is to use m5burner on a separate non-chrome machine to load the firmware, and then have the students upload programs via wifi connection. Thanks!

I'm considering using UIFlow to teach microcontroller programming to high school students. Many of them will be using Chromebooks. Has the browser version of UIFlow been tested with Chromebook OS?