I have multiple ESP32 Dev boards. Some of them require me to manually press the LOAD button. Others will perform the upload automatically. I do have a USB extension cable from the PC to the Dev PCB.
Is there a cap value I can change or something to make Auto Upload work consistently?
Thanks

Hi.
I don’t think so.
I also have both boards, but looking at them, I can’t tell the difference.
It has to do with the internal circuit responsible for putting the ESP32 into bootloader mode. I don’t think you can change that.
Regards,
Sara

You can try to follow this simple hack and see if it solves the issue: https://randomnerdtutorials.com/solved-failed-to-connect-to-esp32-timed-out-waiting-for-packet-header/
Regards,
Sara

There are 2 transistors which are driven by the USB-TTL shifter. I think they are supposed to perform an exclusive OR function which should provide automatic loading. Apparently there is some marginally timing issue which works on some PCB and not on others.
Thanks for your reply

Let me know if you need further help.
Regards,
Sara

What is the Load button?  My boards do not have a Load button?

He’s referring to the EN/RST button.

Thanks Sara.  I went to your very helpful “/solved failed to connect …” page and added the following:
 
I recently had a 36 pin ESP32 WROOM 32 board that failed to boot. The 10 uF capacitor between EN and GND did not make it boot. Then I soldered a 10K resistor in parallel to the 10 uF capacitor and it started to boot.
The resistor cannot be more or less than 10K. The capacitor cannot be less than 10 uF but can be any size larger.
Another 30 pin board i had needed no capacitor but a 4.7K resistor between EN and GND.

There are 2 buttons:   EN/RST (Reset for the CPU) and Boot. The Boot is really misleading as it is really meant to indicate to the CPU that coming out of reset, you are to go into the Load A New Program mode.
The 2 transistors are intended to command the EN and the Load buttons in a specific sequence to allow loading WITHOUT manual intervention. This is done by the host computer toggling the handshake signals in the proper sequence.
The problem is that the crappy parts installed at the factory may not result in the proper timing of the signals to the ESP. 

Very interesting Barry.  By factory do you mean Espressif or the board maker?
 
This leads to the question why in the first place does the ESP32 depend on proper sequencing and timing of RST?  Normally when an RST happens, the flashed code starts running, without any necessary timing of RST.  So the firmware is now running and in control.  Why can’t the firmware detect the handshake signal for an upload?  Or is the handshake signal detected by the USB-UART bridge chip?
 
I have not seen a schematics for a board with two transistors, can you lead me to such a schematic please?
Thanks