Flush Read Buffer Failed...error message..Why?

I am trying to clean up and reset some of the cortex used in my classes. When I try to upgrade the firmwear on my cortex I get errors now. Several of them are giving me “Master firmwear download: flush read buffer failed” Others tell me " No communications link available to vex device, check that your device is connected to pc" sometimes and other times they ( same cortex ) are recognized at the same PC.

This past summer I moved to a new school with new computers. We went from windows xp on older computers to windows 8.1 on brand new dell computers. We are using robotc 4.5.

Any suggestions are appreciated. Thanks in advanced.


Sorry to hear you are having issues. It is likely driver issues during the download when the USB switches from “CDC” to “HID”. Try the Unsigned Windows 8 driver process as described in “276-3245-Windows-8-Driver-Installation.pdf”. It is part of “VEXnet-Key-2.0-Update-Utility-Version-3.0-withInst.zip” and can be found at “http://www.vexrobotics.com/vexedr/software/firmware”. When you get to the “Installing the Unsigned Driver” section, connect a VEX ARM® Cortex®-based Microcontroller, run ROBOTC “Robot / Download Firmware / Manually Update Firmware / Master CPU Firmware / Standard File…” and then run Robot / Download Firmware / Manually Update Firmware / ROBOTC Firmware / Standard File…”. Move the USB cable to the next USB port on the PC and repeat until all USB ports have this done. The PC may have require several minutes to “Device Setup” install all of the drivers each time the USB cable is moved. Similarly plug a Joystick in to each USB port and run the “Robot / Download Firmware / Manually Update Firmware / VEXnet Joystick Firmware / Standard File…” process. After all of this is done, the PC can be rebooted.

If this does not fix the issue, when the PC shows the “Master firmware download: flush read buffer failed” or other error, open the Device manager. Take a screen shot of the Device Manager under Control Panel. Look under Ports (COM & LPT) and under Human Interface Devices. This information can help us decide what to try next.