Arduino IDE - Port disabled (grayed out) for 8266


I have been successfully developing for the Uno board for several years on different Windows 7 computers.

Just got the Sparkfun 8266 Thing Dev board but now stuck in Windows Driver Hell.

I downloaded FTDI driver from this link: How to Install FTDI Drivers -

Tried on 3 different Win7 machines (on which Arduino IDE has worked for years) no luck. On one machine, the Port menu is enabled, and it shows COM3 and COM1 but they don't seem to talk to the board. When I try uploading code to 8266, I get the message:

arning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed

On the other 2 Win7 machines, Port menu is disabled (grayed out).

When I open Device Manager with Uno plugged in, I see the Uno under Ports as COM7. With 8266, I get nothing in Dev Mgr.

I have tried the other Sparkfun pages such as Windows In Depth but that has not helped. I have also looked at the troubleshooting pages on this forum.

Any help appreciated, thanks.

Do you see something in Device Manager under "Other Devices" when you have the SparkFun Thing plugged in?

There was no "Other Devices" section at all on any of the Win7 machines.

Try using a different USB cable or verify the cable you're using works for data on a different device. You might have a defective or charge-only cable.

1 Like

That is entirely possible. I have only a very short micro usb cable, it does power the 8266 but I don't know if it does anything else. I'll try to pick up another one.

1 Like


Used new cable, "Other Devices" shows up in Dev Mgr, Win7 recognizes device, reboot, works fine.

Was not aware of the "charge-only cable" issue.


I'm glad to hear you got it working! I've encountered the same problem, also with a very short micro USB cable.