@kowshik1729 thank you for the hint ! i will check it . schematic picture of my board is given below

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1. no.
2. we are using jumper for gpio 0th pin. please refer the below image.
   

@kowshik1729 sorry, gpio 0 is low only till it is programmed. after that this will disconnected.

@kowshik1729 thank you for the hint ! i will check it . schematic picture of my board is given below

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@kowshik1729 Yes i m programming the board first time using arduion. GPIO 0 is low all the time.

And having one more doubt !
Bootloader for esp32 will present already or we need to load the bootloader code into the newly brought esp32 chip ?

Hi All, i m also facing the same error. we are developing an iot device based on esp32d0wdq6 controller. we have designed a board. Now the program is not getting uploaded. the connections are
TTL Converter 3.3v - vcc (ESP32)
TTL Converter gnd - gnd (ESP32)
TTL Converter TXD - RXD (ESP32)
TTL Converter RXD - TXD (ESP32)
GND - GPIO 0 (ESP32)
3.3V - EN (ESP32).
Connecting......................................____An error occurred while uploading the sketch
_
this is error message i m getting.

A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header
FYI, we are using the W25Q40CL flash ic. please help me to sort out this issue.
Thanks in Advance !