How to fix "Warning: cannot find entry symbol Reset_Handler; defaulting to 0000000008000000"

[LJohn.1]

I created a new project in STMCubeIDE, and I get the above warning. I have the startup file in my project, and it has Reset_Handler defined. I looked through all the project properties, and I didn't notice anything was wrong.

Can someone tell me why my project can't find the Reset_Handler?

[LJohn.1 · Accepted solution]

I just fixed my own issue. Just in case anyone else encounters this, here's the solution.

I needed to add the folder containing my start-up file to project properties->Paths and Symbols->Source Location

[DJC]

For me it was the /core/startup/ folder was entirely missing.

I fixed it by making a new project with the same MCU, then copying the folder to my own project.

But, yeah, your answer helped me find the problem, so thanks!

[paul19]

Handlers are defined in an assembler startup file, which is generated automatically by STM32CubeIDE or STM32CubeMX. The file is located in a folder called "Startup" at the root of your project. It is named after your MCU, for example startup_stm32f303xe.s, startup_stm32l476rgtx, etc.

The warning "cannot find entry symbol Reset_Handler" means the startup file is either 1. corrupted, 2. missing, or 3. not included in your build. To fix cases 1 and 2, simply re-generate the code from STM32CubeIDE or STM32CubeMX.

Case 3 is more interesting. Upon code generation, STM32CubeIDE and STM32CubeMX sometimes mark the "Startup" folder as "Exclude from build". To make things worse, the folder doesn't have the "excluded" icon, so there's no obvious way to notice it. So you need to right-click the "Startup" folder, go to "C/C++ Build" and uncheck the "Exclude resource from build" checkbox. This issue seems to arise randomly, often with projects copied from other projects.

[liteyear]

In my recent experience with STM32CubeIDE 1.16.1, STM32CubeMX 6.12.1, and STM32Cube MCU Package (for STM32U5 Series) 1.6.0, CubeMX does not generate the startup file. I discovered this by following the instructions for porting a project to a new MCU. That involves using STM32CubeMX to create a STM32CubeIDE project from the ioc file. The startup file and folder was missing. Later I noticed the FLASH and RAM ld files were missing too.

I spent some time trying to delete, rebuild, generate, generate, generate, in CubeIDE and CubeMX, following every process I could think of or find. The files never appeared.

Eventually I created a new project (from an existing ioc file) in STM32CubeIDE, and the files appeared.

I wondering now whether this was always the case - does CubeMX not touch these files?