A fatal error occurred: Failed to connect to ESP32: No serial data received.

[langenegger]

Hi,

I have an ESP32 cam board with an ESP32 expansion board. When uploading with Arduino, I always get the error “A fatal error occurred: Failed to connect to ESP32: No serial data received.”
I've been trying for hours without success.
My Arduino board: ESP32 Wrover Module

1. Press BOOT.
Arduino to upload.
While “Connecting...” appears → Release BOOT

2nd method:
Press BOOT
Reset
Hold BOOT for 1 second
Release
Restart upload

CH340 driver installed
ESP32 is displayed in the COM port

What could be the cause?
Thanks for any help
Regards
langenegger

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[horace99]

I found that the latest drivers installed on Windows 10 and 11 don't work with some dev boards using the CH340, e.g. a ESP32-CAM and some ES8266
I rolled back the driver following instructions in https://learn.sparkfun.com/tutorials/ho ... rivers/all to version 3.4.2014.8
win10 and 11 then communicated with the dev boards OK

[langenegger]

Thanks for the tip. I have now installed the driver version 4.2014.08 and restarted. Unfortunately, without success.

[langenegger]

Some additional information:
I have a smart car from Tscinbuny. Uploading the script for the development board works correctly with Arduino. There is also an ESP32 Cam with an ESP32 expansion board. When loading the corresponding script, the following error always occurs. “A fatal error occurred: Failed to connect to ESP32: No serial data received.” The following applies: Arduino board: esp32 Wrover module Baud rate 115200 All variants with boot or reset pressed Com port is displayed in CH340 version 3.4.2014.8. USB cable is checked and correct.

[lbernstone]

In the tools menu, choose the port for your device. Open the Serial Monitor and make sure that when you hit reset, you see boot log info in the monitor.
Unplug the ESP32, hold down the boot button, and plug it back in. You should see "Waiting for download..." on the monitor.
The device should then be in a state to take programming, even it has a faulty firmware on board.
If it does not, then post the boot log back here.

[langenegger]

When I press the reset button, nothing is displayed in the serial monitor. There is no response.

[lbernstone]

Bad cable or bad connections
Test the cable on something else; make sure you can transmit and receive data over it.
If the USB->UART is showing up in devmgr, and driver has no errors, then the device sounds dead.