Troubleshooting: My core only ever flashes yellow, what's up?

Hey All!

This problem should be very rare, but I wanted to post this here in case anyone is seeing this issue. How do you know your core has this problem?

  • Your core is flashing yellow when powered.
  • It simply won’t stop, even if you do a factory reset, or put the core into listening mode

If you’re seeing this, I’m working on a tool to make recovering easy, and I’m also working on documentation so you can resolve this issue manually in the meantime. Until that goes up please email me at, and I’ll help work through the issue with you.


Hey All,

We’re seeing a number of cores with this issue resolved with a quick factory reset as well.

Try holding down both buttons on the core, and release the reset button. Keep holding the other button as it flashes yellow, and keep holding it until the core starts fast flashing white, then release the mode button. When your core resets, it should be slow blinking blue and in listening mode.


Mine appears to be forever flashing green (maybe its yellow?)
On reset it instantly goes back to flashing.
On factory reset (after the white flashing) it goes back to flashing yellow/green,
Holding the mode button alone for 3 or 10 or 20 seconds does nothing to the flashing Green/Yellow.

It did connect to my network once, so i know its capable

Same problem?


I think Ozzy and I are communicating directly over email, just so nobody thinks this has gone unanswered. :smile:

Any solutions? I’m getting a yellow flash except if I use dfu-util to replace the firmware, whereupon it goes through the full connect to network routine before failing and returning to the yellow flash.

Hi @Andriod,

If you’ve flashed firmware to your core and it’s done the connect to the network routine, it’s possible it’s flashing orange (which looks somewhat like yellow). The orange flash signifies that the server doesn’t have the right public key for your core. This thread has become somewhat buried, but there are some steps here:

No dice, I’m not even sure I can get the dfu mode properly connected. At least the step where I was supposed to copy off the old ID failed with:

Cannot open device
Opening DFU capable USB device…

No file was created.

@Android It sounds like you’re trying to use dfu-util to get the Core ID, but dfu-util is for programming the Core; you should use some kind of a serial terminal to get the Core ID.

Can you describe exactly the behavior you’re seeing, as verbose as possible? I’m not certain exactly what issue you’re running into; if we have more information we should be able to help.

I got it to a nice orange flash and sent an e-mail to David & hello, the error I mentioned was from not using sudo on dfu-util. At present it’s flashing blue, but would descend in a death spiral to orange or yellow if I tried to get it online.