Arduino: 1.8.13 (Windows 10), Board: "Generic ESP8266 Module, 80 MHz, Flash, Legacy (new can return nullptr), All SSL ciphers (most compatible), dtr (aka nodemcu), 26 MHz, 40MHz, DOUT (compatible), 1MB (FS:64KB OTA:~470KB), 2, nonos-sdk 2.2.1+100 (190703), v2 Lower Memory, Disabled, None, Only Sketch, 115200"

Executable segment sizes:

IROM   : 228624          - code in flash         (default or ICACHE_FLASH_ATTR) 

IRAM   : 26756   / 32768 - code in IRAM          (ICACHE_RAM_ATTR, ISRs...) 

DATA   : 1248  )         - initialized variables (global, static) in RAM/HEAP 

RODATA : 688   ) / 81920 - constants             (global, static) in RAM/HEAP 

BSS    : 24880 )         - zeroed variables      (global, static) in RAM/HEAP 

Sketch uses 257316 bytes (26%) of program storage space. Maximum is 958448 bytes.

Global variables use 26816 bytes (32%) of dynamic memory, leaving 55104 bytes for local variables. Maximum is 81920 bytes.

esptool.py v2.8

Serial port COM3

Connecting........_____....._____....._____....._____....._____....._____.....____Traceback (most recent call last):

  File "C:\Users\Reghunaath A A\AppData\Local\Arduino15\packages\esp8266\hardware\esp8266\2.7.2/tools/upload.py", line 65, in <module>


  File "C:/Users/Reghunaath A A/AppData/Local/Arduino15/packages/esp8266/hardware/esp8266/2.7.2/tools/esptool\esptool.py", line 2890, in main


  File "C:/Users/Reghunaath A A/AppData/Local/Arduino15/packages/esp8266/hardware/esp8266/2.7.2/tools/esptool\esptool.py", line 483, in connect

    raise FatalError('Failed to connect to %s: %s' % (self.CHIP_NAME, last_error))

esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header

esptool.FatalError: Failed to connect to ESP8266: Timed out waiting for packet header


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I'm getting the above stated error message while I'm trying to upload a code to esp8266 via an arduino(I've removed the ATMEGA32 from my arduino). Sometimes it gets uploaded without a problem(very rarely) but mostly the upload fails. I connected rx of arduino to rx of esp and same for tx too. 3.3v of arduino to enable and vcc of esp. graund of arduino to ground of esp and gpio0.

The code that I'm trying to upload:

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);     // Initialize the LED_BUILTIN pin as an output

// the loop function runs over and over again forevervoid lop() {
  digitalWrite(LED_BUILTIN, LOW);   // Turn the LED on (Note that LOW is the voltage level
  // but actually the LED is on; this is because
  // it is active low on the ESP-01)
  delay(1000);                      // Wait for a second
  digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
  delay(2000);                      // Wait for two seconds (to demonstrate the active low LED)

My settings: enter image description here

EDIT: Also, I want to add one more thing when the message box says "Connecting........_____....._" during that time if i reset the esp the code starts uploading

  • @jsotola bruh half of my question is missing. Let me update it. Jul 20, 2020 at 5:32
  • @jsotola please check it out now. Jul 20, 2020 at 5:53
  • do you put the esp8266 in flashing mode?
    – Juraj
    Jul 20, 2020 at 11:41
  • @Juraj yes I connected the esp0 to groung Jul 20, 2020 at 12:24
  • io 0 to gnd, then reset?
    – Juraj
    Jul 20, 2020 at 13:08

1 Answer 1


You need to set esp 8266 to flash mode.
Please connect en PIN to Gnd pin.
Then flash again.

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