Serious issue with Vexnet - Master Code 4.23

Recently, we updated one of our robots’ master code (both the Cortex and the associated Joystick) to 4.23 using the 4.1.5 Vexnet Upgrade Utility. After the update, the Vexnet keys will not pair at all. Tethering works fine, but neither the old black keys nor the new white keys will pair. The only solution was to revert the code back to 4.22 using the 4.1.2 Vexnet Upgrade Utility, after which it works just fine.

Strangely, the indicator lights on the Vexnet keys themselves do not turn on until after the joystick and Cortex have declared an error (Two red lights, slow blink; translates as “Partner Not Found” on the Cortex and “Vexnet Key Not Found” on the Joystick).

We have tested this with multiple Cortexes, Joysticks, Vexnet keys (both black and white) and even tethers. In all cases the 4.23 code will not pair and the 4.22 works without any problems.

Our problem is the same as this one in another thread:

You must update both the Cortex and Joystick to version 4.23 and the White Keys to version 1.46.

If the 2 Red LEDs are the “Joystick” and “VEXnet” on the Joystick - this indicates the Radio Key and Joystick Code is not compatible. Likewise, if the 2 Red LEDs are the “Robot” and “VEXnet” on the Cortex - this indicates the Radio Key and Cortex Code is not compatible. We are working on a revision to the Users Guide to define these blink patterns which should be out soon.

After updating both the Units and the White Keys to the latest version should correct this issue. Let us know if you are still having problems after updating.


The updated User Guide can now be downloaded at: The Guide now contains the Blink Codes for code compatibility.


So the keys themselves need to be updated? Do we just plug them into a USB port and run the update utility then?