Hi Sara & Rui,
Thanks for your explanation about OTA on ESP8266 using Arduino sketch (to find the compiled file to upload).
I have some problem after adding OTA to my sketch that connects my ESP8266 to Raspberry using MQTT/nodered : all runs perfectly except the callback function. This sketch reads temperature sensors (DS18B20) and receives commands (by callback from the raspberry) for relays. Before I added OTA this callback function worked but now with OTA the callback receives nothing. Do you know the reason why ?
What library are you using for MQTT?
Maybe the two libraries conflict.
For specific issues related to the OTA library, I recommend posting an issue on the library issues page. Here is the link: https://github.com/ayushsharma82/AsyncElegantOTA/issues