No interrupt.c file
When I create an empty C project, 4 source files are generated, including the stm32l0xx_it.c, with the SysTick_Handler function in it, allowing interruptions.
Maybe you can try to create another empty project, copy its interrupt source file and paste it in your project? I’m not sure this solution works but you could try this.
Maybe it depends on the board you’re working on ? (I have a L0 model)
Hope it helps a bit.
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