cannot upload sketch to ESP32

Hi ferry, this kind of problems mainly arise because of faulty USB cable or wrong connections. Sometimes when you buy a USB cable it is only manufactured for Charging i.e. Vcc an Gnd Line are present. and they don't have the DATA lines(D+, D-). 

in your case if i consider the faulty USB cable then you are trying to upload the sketch but because of absense of data lines, the data is not reaching to ESP32. I would recommend either you check the connections or you should change the USB cable and try again. please let me know if this works out.

I also faced these kind of issues with my ESP8266 and as well as ESP32 development boards. There are some points we have to keep in mind that we must select a high quality USB for uploading firmware in these boards. The other problem occurs especially in ESP32 boards is that when the uploading starts, you need to press the boot button on the board to start uploading your sketch. I faced this issue with my newly purchased board, I check for that issue on some forums, from where I got a response that for uploading firmware in ESP32, need to press boot button. Here I suggest you to get connect with the SSLA platform technical support team for getting better assistance regarding your queries and project support.

You can crosscheck few things as directed:

1. Check the available port number, if it in not available then your USB cable is faulty.

2.Check if you have selected ESP32 under device or not.

3.If 1 and 2 are Verified, then long press the BOOT button on ESP32 after pressing uploading, until it is showing "Uploading".

The ESP32 has a few common problems, specially when you are trying to upload new sketches or install the ESP32 add-on on the Arduino IDE. This guide is dedicated to the ESP32 when programmed with Arduino IDE. Here, we provide a compilation with some of the most common problems with the ESP32 and how to fix them.
There’s an add-on for the Arduino IDE that allows you to program the ESP32 using the Arduino IDE and its programming language. Follow one of the next Units to prepare your Arduino IDE to work with the ESP32 in your operating system. If at this moment you can’t find your ESP32 board name, we recommend repeating the installation process from scratch.

I also faced these kinds of issues with my ESP8266 and as well as ESP32 development boards. There are some points we have to keep in mind that we must select a high quality USB for uploading firmware in these boards. The other problem occurs especially in ESP32 boards is that when the uploading starts, you need to press the boot button on the board to start uploading your sketch? I faced this issue with my newly purchased board, I checked for that issue on some forums, from where I got a response that for uploading firmware in ESP32, I need to press the boot button. Here I suggest you a new advanced product by Sierra Software Ltd. Platform named EFB-IoT, you can also get connected with their technical support team for getting better assistance regarding your queries and project support.