IT'S WORKING!!

I just made a new project in the SW4STM32 and it includes the correct startup file with all the interrupt vectors. The firmware still doesn't have startup_stm32f103x8.s file and the name of the file in startup folder is startup_stm32.s but now it has all the interrupt vectors and other definitions.

The problem has vanished now and the interrupt is working like a charm. 🙄

But I am still skeptic of why the startup file was missed in the first try.

The startup_stm32.s file has the following comment in the beginning, so I am relieved.

/**
******************************************************************************
* @file startup_stm32.s dedicated to STM32F103C8Tx device
* @author Ac6
* @version V1.0.0
* @date 2018-04-05
******************************************************************************
*/