Undefined reference to `app_main'

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1

When trying to create a blank project, I always get undefined reference to 'app_main'. When I select Arduino as framework it works but not with idf. Maybe it is because of the new idf 5.X version? If yes, how to change that during project setup?

2

Can you pload your project files? (Without .pio folder)

3

Using VS Code Version: 1.80.1 (Universal)
Platformio: Core 6.1.9 Home 3.4.4

4

Can you replace the contents of the src/CMakeLists.txt with

idf_component_register(SRCS "main.c"
                    INCLUDE_DIRS ".")

?

1 Like
5

Sadly gives me the same error:

/esp/esp-idf/components/freertos/port/port_common.c:135: undefined reference to `app_main'
collect2: error: ld returned 1 exit status
ninja: build stopped: subcommand failed.
6

Hi Iā€™m here with the same error. And Iā€™ve googling it for days without any solution.

esp/esp-idf/components/freertos/app_startup.c:206: undefined reference to `app_mainā€™

how can it be that hard to solve this problem ??

I have the main.c file

void app_main(void)
{
printf(ā€œHello world!\nā€);

sem_vsync_end = xSemaphoreCreateBinary();
assert(sem_vsync_end);
sem_frame_buffer_ready = xSemaphoreCreateBinary();
assert(sem_frame_buffer_ready);

}

Iā€™ve rename it to app_main.c and app_main.cpp. Everytime I do it. Iā€™ve update the CMake file. PIO and VScode and ESP-IDF all of them are up to date. What do we missing?

This file was automatically generated for projects

without default ā€˜CMakeLists.txtā€™ file.

FILE(GLOB_RECURSE app_sources ${CMAKE_SOURCE_DIR}/src/.)

idf_component_register(SRCS ${app_sources})

idf_component_register(SRCS ā€œapp_main.cppā€
INCLUDE_DIRS ā€œ.ā€)

7

IT WORK FOR MEā€¦!!! DAMM i been having a long week trying to figure that outā€¦

Thanks so Much

8

What worked for you? I donā€™t see where\how the issue was resolved.

9

The error usually comes from either the source file containing the app_main() function not being compiled due an error in your CMake files, or the function being defined in a .cpp but lacking the extern "C" (the function needs to have C linkage). Post your whole project files if youā€™re still having problems.