The problem is solved by blocking the Autoreset. The 120 ohm resistance must be connected between the RESET pin of Arduino and +5 V, while the 10µF capacitor is connected with the positive pole to the RESET of Arduino and negative to GND.
With a jumper cable connect on Breadboard the RESET signal of Arduino.
The methods described should be used only if absolutely necessary.
Important note: the need to connect these components only when needed, is dictated by the fact that to load a sketch on the Arduino should autoreset, otherwise the upload will fail and we will get the error avrdude: stk500_getsync (): not in sync: resp = 0×00 – avrdude: stk500_disable (): protocol error, expect = 0×14, resp = 0×51, so if you see this error, know that you just have to “liberate” the pin “RESET” Arduino from the link with the Anti- autoreset.
[Thanks to Michele Menniti]