Your vehicle is not responding.restart the vehicle

I am also experiencing this problem.
I am using a Pixhawk 4 by holybro flight controller, and the PX4 was able to pair with the QGC previously over USB, even managed to get some manual flight test done.

I wanted to install a rangefinder to it, so I changed the SENS_ENSF0X & SENS_EN_SF1XX parameters to SF10/a. Upon changing QGC informed to restart PX4 for changes to apply which I did by disconnecting from USB and reconnecting(no external power/batt to the PX4). Once reconnected USB PX4 & GPS lights up, gives the sound to indicate ready but QGC shows this error.

I have tried closing QGC, connecting PX4 via USB, then launching QGC, still unable to view data of the PX4 on QGC. I have also tried updating the firmware but still shows this error. Also tried this on multiple PCs(Mac OSMojave & Windows 10).

Anyone knows why this error is showing up and how to resolve it?? Thanks.

first you connect usb cable to pixhawk . then go to firm ware update firmware then will show two firmwares one is px4 flight stack another one is ardupilot firm ware you select ardupilot firmware upload it . you get output

Ok, I tried that but the strangest thing happened.

Tried firmware update to Ardupilot on NuttX, it attempted to download the firmware from the website but eventually said file cannot be found. I tried Ardupilot on ChibiOS, it did the same thing. Tried firmware update back to PX4 firmware, same thing again.

It started to look like QGC was having a problem, so I reinstalled QGC and tried again, this time could update to all available firmwares, and I am able to get the data on QGC.

Not too sure why it did that, moreover, previously when I was not able to get any data, I tried connecting to QGC on another PC it had the same issue there. I am not too sure what caused it, will have to check on my other PC later. might have been a bug.

Anyways PX4 is able to talk with QGC again, thanks for the input.

thank for the given reply, now am already do that but no use i con’t fly a autopilot

Just an FYI, figured out what was the main issue I was experiencing. Every time I change SENS_ENSF0X to a different value than unknown0, once restarted to apply the change, PX4 doesn’t talk to QGC, not sure why this happens though, may be another parameter that is interfering with this??