Esp32cam Failed to connect to ESP32: Timed out waiting for packet header

Pre-requisites for flashing:

• ArduinoIDE 1.8.12
• Core ESP32 1.04 (at time of writing)
• Select board AI Thinker Cam
• uplooad speed 921600
• freq 240Mhz
• flashfreq 80Mhz
• mode QIO if not working try DIO
• partition scheme default
• Serial monitor is closed
• NO hardware connected to the pins of the ESPcam
• Make sure the USB cable is a data cable and NO loading cable only
• check Windows device manager if programmer is shown and has max speed / 8n1 hardware

Connections

    FTDI    -   ESP32
    GND         GND
     5V          5V
    TXD         UOR
    RXD         UOT

If you use an AIThinker Cam clone you have to ground GIPO 0:

• connect GPIO 0 with a dupont wire connected to GND
• press reset
• compile and upload (use AI THINKER CAM)
• optional:
  • press reset
  • upload filesystem data (SPIFFS)
• disconnect GPIO 0 and GND
• press reset
• code should execute

And yes you have to do it every upload, on my dev board I soldered a little switch with proper isolation
Some more solutions from experience:

• If there is still a problem use a 10K (or so) pull-down resistor between RX0 and GND (test on breadboard before soldering)
• Pressing and holding (!) the boot-button while uploading on some "bad" boards
• Happened with a "normal" ESP32 board to me - just to be sure - I got an ESP8266 in an ESP32 packaging. Configuring for the ESP8266 solved the issue of uploading.

I have delved for a solution in this regard for weeks and it seems I have a solution.

Findings-

1. FTDI module is probably faulty or not supported for each instance.
2. Aithinker Board is not compatible with esspressif (use ESP32Wrover, more details below )

I have an esp32cam from Esspressif, not Aithinker.

I was trying with FT232rl , No matter what Voltage/jumpers/USB cable I used, it didn't work. Always stuck with fatal timed out error.

After many futile attempts with FTDI breakout, I gave my Arduino UNO a try (please note my UNO has mega16u2 chip as USB serial chip (top right corner just beside the oscillator) and fortunately it worked.

I have read that CP2102 is also working.

                        **Here are the steps to follow-**

1. Arduino ESP32Cam connections

   3.3 Arduino --------- 3v Esp32CAM 
   GND Arduino ------------ GND Esp32CAM
   RESET Arduino to Ardunio GND
   RX Arduino -------------- VOR Esp32CAM (this is not a mistake RX to rx & TX to tx)
   TX Arduino -------------- VOT Esp32CAM
   GPIO 0(zero)(written as IO0) Esp32CAM to GND Esp32CAM 
   

2. I didn't have any need to press the reset button in any part of the operation before & during uploading.

3. I am assuming You have pre-installed the esp32 board manager.

• Now select the correct COM port where your Uno (in this case) is plugged in.

• Select the correct board as mentioned

    Tools>Board>ESP32 Arduino > select ESP32 Wrover Module
  

• Some uploading setups are to be Done (Under Tools, these will only appear when the Wrover module is selected )

   Upload speed -- 115200
   Flash Frequency -- 40Mhz
   Flash Mode -- QIO
   Partition Scheme --- Huge App
   Port ---- select the right com port for your breakout or UNO
  

JUST press upload and relax

After a while, you will be able to see this message

        Leaving...
        Hard resetting via RTS pin...

• Disconnect the Esp32Cam GPIO 0 and GND
• Power the ESP32Cam with 5/3v with external power supply (Arduino or other breakouts may not be able unless you are connected with a Powered USB Hub)
• keep TX, RX, & GND of the 2 boards connected, don't disconnect Arduino Reset and GND.
• Press Reset on ESPCAM and open Serial monitor and you will be able to see the IP address of the cam if it was configured with your wifi correctly.OR get any network scanner App on android or windows.

I hope it helped.

In my case I forgot to remove the SD card. Other users recommended removing unnecessary connections to the pins-- and the SD card technically uses some of those :)

This was solved by using other jumpers. It seems one of the jumpers used in the wiring was faulty.

If you're having the same issue and tried everything in this post, try checking your cables!

If you try it with arduino it works but its needed to press reset button on esp32 before you upload your code

Basically I was facing the exact same problem fro quite some time. What worked for me was that as the chip was flashing, shifting the power wire from 5V to 3V3 pin. I do not know why but it workes. When esptool starts flashing at 2%, switching the cable just then, despite having 5V from supply into the 3V3 point made the flashing successful. I do realize this is probably a bad answer to your problem since it involves oversupplying voltage to the chip on the wrong point as it is flashing and could damage the chip. However, if anyone is tired of debugging and are at the point where you are considering throwing the chip away, might as well try my method. For other's who value their chip, don't try this method and if you still do, kniw it is at your own risk. But it worked for me after 3 days of just messing around with connections.