How do i fix the "A fatal error occurred: Failed to connect to ESP32: Timed out waiting for packet header"
ESP32 only works with 3.3 V serial do not switch the FTDL voltage to 5 V

Watch out for the serial connections too

U0R-->TX

U0T-->RX

If you mixed it up it won't work!

First of all you need to connect two pins only when uploading
It is all ready fixed for you need to press the rest button when uploading
and seeing these dots as below image. 


ESP32-CAM on-board RST button Press and hold until you see uploading




After a few seconds, the code should be successfully uploaded to your board.

I hope this helped for you!

You can reffer to this link for more info

https://randomnerdtutorials.com/esp32-cam-take-photo-display-web-server/