The firmware update over WiFi is called OTA update. OTA stands for "over the air". The esp8266 can OTA update itself. The Arduino library for this is called ArduinoOTA and it is bundled with the ESP8266 Arduino boards support package. See the example for ArduinoOTA library in IDE Examples menu. Other MCU have the self update option too. ESP32 has ...


I have solved the issue by selecting, Tools > Processor > ATMega (Old bootloader) @Juraj, Thank you for suggestion.

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