Error 3902 writting the data to serial

[Juan_Antonio]

Is your arduino original or a clone?

Why the inventor does not work with the Arduino by connecting to the uart port ,,Note that there is a connection on the Serial USB Terminal application ???

Serial component works with original Arduino UNO, but it doesn't work with many clones, for example those with CH340/CH341 chip. It has also worked for me with the CP2102 module. For other devices, use the extension that Chris has recommended, here are several examples: https://community.appinventor.mit.edu/t/serial-otg-arduino-ch340-ftdi-rkl099s-extension/21156