`build/Kconfig` not generated → Kconfig error during `idf.py reconfigure` (ESP-IDF v5.5.1) (IDFGH-16830)

[lbussy]

Answers checklist.

• I have read the documentation ESP-IDF Programming Guide and the issue is not addressed there.
• I have updated my IDF branch (master or release) to the latest version and checked that the issue is present there.
• I have searched the issue tracker for a similar issue and not found a similar issue.

IDF version.

v5.5.1

Operating System used.

macOS

How did you build your project?

Other (please specify in More Information)

If you are using Windows, please specify command line type.

None

What is the expected behavior?

When configuring a project using ESP-IDF v5.5.1, the build system generates a build/kconfigs.in file that includes:

source "/<project-path>/build/Kconfig"

However, he file build/Kconfig is never created, causing kconfgen to fail with a KconfigError during idf.py reconfigure (and also during initial configuration). Manually creating an empty build/Kconfig allows the configuration to succeed.

This appears to be a regression or oversight in how ESP-IDF populates its COMPONENT_KCONFIGS list when generating kconfigs.in.

• ESP-IDF should not reference build/Kconfig unless the file is actually produced during the configuration process, OR
• ESP-IDF should auto-generate a minimal build/Kconfig file before writing a source statement to kconfigs.in.

What is the actual behavior?

build/kconfigs.in contains:

source "/Users/<user>/.../arduino_idf_demo/build/Kconfig"

build/Kconfig does not exist.

Running idf.py reconfigure fails:

kconfiglib.core.KconfigError: kconfigs.in:80:
'/.../arduino_idf_demo/build/Kconfig' not found
(in 'source ".../build/Kconfig"')

Creating an empty file:

touch build/Kconfig

... allows the configuration to succeed.

Steps to reproduce.

1. Create a project using ESP-IDF v5.5.1.

2. Add any component containing a valid Kconfig file, e.g.:
   components/drd_handler/Kconfig

3. Remove build/, managed_components/, and dependencies.lock.
   rm -rf build managed_components dependencies.lock

4. Run:
   idf.py -D CMAKE_EXPORT_COMPILE_COMMANDS=ON reconfigure

5. Observe the error from kconfgen.

6. Inspect build/kconfigs.in and notice the reference to build/Kconfig.

7. Create an empty file:

   mkdir -p build
   touch build/Kconfig

8. Re-run idf.py reconfigure and observe that it succeeds.

Build or installation Logs.

Excerpt from `build/kconfigs.in`:

...
78  source "/Users/.../esp-idf/components/wear_levelling/Kconfig"
79  source "/Users/.../esp-idf/components/wifi_provisioning/Kconfig"
80  source "/Users/<user>/.../arduino_idf_demo/build/Kconfig"
81  source "/Users/<user>/.../arduino_idf_demo/managed_components/espressif__esp-dsp/Kconfig"
...

Error traceback:

kconfiglib.core.KconfigError: kconfigs.in:80:
'/Users/<user>/arduino_idf_demo/build/Kconfig' not found
(in 'source "/Users/<user>/arduino_idf_demo/build/Kconfig"').
Check that environment variables are set correctly (e.g. $srctree).

Diagnostic report archive.

Running idf_diag in directory /Users/<user>/Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo
Executing "/Users/<user>//.espressif/python_env/idf5.5_py3.14_env/bin/python -m esp_idf_diag create --no-hints --force-terminal --project-dir /Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo --build-dir /Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build --output idf-diag-4ea28ecb-57d1-491d-8a4d-2bd86e68c9e9"...
Creating report in "idf-diag-4ea28ecb-57d1-491d-8a4d-2bd86e68c9e9" directory.
Searching for device serial port ...
Serial port: /dev/cu.usbserial-210
Shell environment information
* Enviromental Variables
* Python Environmental Variables
Basic ESP-IDF information
* ESP-IDF Version
* ESP-IDF Git Version
IDF Component Manager information
* IDF Component Manager
ESP-IDF project information and artifacts
* Project Description
* Compile Commands
* Linker Scripts
warning: File "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/esp-idf/esp_system/ld/sections.ld" does not exist: [Errno 2] No such file or directory: '/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/esp-idf/esp_system/ld/sections.ld'
* Flash Arguments
* Sdkconfig
* Logs
warning: No files with content matching regex "^Command: ninja all$" found in "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/log"
warning: No files with content matching regex "^Command: ninja all$" found in "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/log"
warning: No files with content matching regex "^Command: ninja flash$" found in "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/log"
warning: No files with content matching regex "^Command: ninja flash$" found in "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/log"
warning: No files with content matching regex "^Command: .*idf_monitor.py.*$" found in "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/log"
warning: No files with content matching regex "^Command: .*idf_monitor.py.*$" found in "/Users/<user>//Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build/log"
* Link Map File
warning: No files matching glob "*.map" found in "/Users/<user>/

/Library/CloudStorage/OneDrive-Personal/Documents/GitHub/arduino_idf_demo/build"
ESP-IDF python and virtual environment information
* Python Version
* Python Virtual Environment Packages
System information
* Platform Information
* Darwin Information
Target information
* Esptool - flash_id
* Esptool - get_security_info
warning: Exec command "esptool.py --port /dev/cu.usbserial-210 get_security_info" failed with exit code 2
* Espefuse - summary
ESP-IDF tools information
* ESP-IDF Tools Info
The report has been created in the "idf-diag-4ea28ecb-57d1-491d-8a4d-2bd86e68c9e9" directory.
Please make sure to thoroughly check it for any sensitive information before sharing and remove files you do not want to share. Kindly include any additional files you find relevant that were not automatically added. Please archive the contents of the final report directory using the command:
"idf.py diag --zip idf-diag-4ea28ecb-57d1-491d-8a4d-2bd86e68c9e9".

idf-diag-4ea28ecb-57d1-491d-8a4d-2bd86e68c9e9.zip

More Information.

Environment

• ESP-IDF version: v5.5.1

• Target: ESP32

• Host OS: macOS

• Python: 3.14.0 (managed by IDF’s virtual environment)

• Build system: CMake + Ninja (via idf.py)

• Removing a project-root Kconfig.projbuild does not remove the erroneous reference to build/Kconfig.

• The project’s component Kconfig files are valid.

• The issue appears to originate from the content of build/config.env, where COMPONENT_KCONFIGS includes:
  ...;<project>/build/Kconfig;...
  even though that file does not exist and is not written by any part of the IDF build pipeline.

• The workaround is to create an empty build/Kconfig before running idf.py, but this should not be required.

Suggested Fix:

• Modify ESP-IDF’s Kconfig aggregation logic so that build/Kconfig is not included in COMPONENT_KCONFIGS unless generated.

• Or ensure that a minimal build/Kconfig is created before generating kconfigs.in.

• Or filter out invalid/nonexistent paths before writing the list into kconfigs.in.

Minimal Project Tree

.
├── CMakeLists.txt
├── cleanproject.sh
├── components
│   └── drd_handler
│       ├── CMakeLists.txt
│       ├── drd_handler.cpp
│       └── Kconfig
├── main
│   ├── CMakeLists.txt
│   └── main.cpp
├── sdkconfig
├── sdkconfig.defaults
└── partitions_16mb.csv

Minimal repro project:

espidf_kconfig_repro.zip

[Honza0297]

Hello @lbussy and thank you for your detailed issue description!
I have tried to reproduce your issue on my linux machine; unfortunately, I haven't been successful. I will now find a MacOS machine to test this issue on and let you know with further information.
Thank you for your patience!

[Honza0297]

We are unable to reproduce this issue even on MacOS machine.
I see in the idf-diag output that your version is ESP-IDF v5.5.1-dirty - the dirty means that the local copy of your ESP-IDF is different from the upstream (either it is not up to date or there are some local changes). Can you please ensure your branch is updated (or, if you made any local changes to ESP-IDF, these changes are not causing any problems)? If you are not sure, I'll be happy to provide help.

[fhrbata]

Hello @lbussy ,

does the arduino_idf_demo component by any chance call idf_component_register with the KCONFIG option?

There should be no Kconfig files in the build directory. The Kconfig file is always referenced to its original location in the component directory.

The problem could be if the Kconfig is explicitly provided in the idf_component_register call, for example like

idf_component_register(SRCS "hello_world_main.c"
                       PRIV_REQUIRES spi_flash
                       KCONFIG Kconfig
                       INCLUDE_DIRS "")

If the config file has the default name Kconfig it is included automatically and does not need to be explicitly referenced, but it should of course not cause any problems. The problem seems to be when the absolute path for the KCONFIG option is obtained during early evaluation. The code is using get_filename_component

get_filename_component(__component_kconfig "${__component_kconfig}" ABSOLUTE)

When the BASE_DIR dir is not provided, cmake uses CMAKE_CURRENT_SOURCE_DIR. Problem is that the early evaluation is done is cmake script mode and here the CMAKE_CURRENT_SOURCE_DIR is set the the build directory.

When run in cmake -P script mode, CMake sets the variables CMAKE_BINARY_DIR, CMAKE_SOURCE_DIR, CMAKE_CURRENT_BINARY_DIR and CMAKE_CURRENT_SOURCE_DIR to the current working directory.

If this is the root cause of the problem you are seeing, you can try to work around it by removing the KCONFIG option from the idf_component_register call or refer to the Kconfig with absolute path e.g. with KCONFIG "${CMAKE_CURRENT_LIST_DIR}/Kconfig".

The problem could be of course somewhere else, but the location of the Kconfig file in the build directory suggests that this might be the reason.

Thank you

[lbussy]

does the arduino_idf_demo component by any chance call idf_component_register with the KCONFIG option?

Aye, it does. When I get some coffee in me, let me have a look and see if poking there will make my problem go away.

I lied, I thought it did. These are all of the CMakeLists.txt in my project:

main:

idf_component_register(
    SRCS "main.cpp"
    INCLUDE_DIRS "."
    REQUIRES
        drd_handler
        logging
        wifi_manager
        http_server
        captive_dns
        espressif__arduino-esp32
)

wifi:

idf_component_register(
    SRCS "wifi_manager.cpp"
    INCLUDE_DIRS "include"
    REQUIRES
        esp_wifi
        esp_netif
        nvs_flash
        captive_dns
        espressif__mdns
        logging
    PRIV_REQUIRES espressif__arduino-esp32
)

logging:

idf_component_register(
    SRCS
        "logging.cpp"
        "log_wrap.cpp"
    INCLUDE_DIRS
        "include"
    REQUIRES
        log
)

# Ensure our wrapper functions are used for esp_log_write / esp_log_writev
target_link_options(${COMPONENT_LIB} INTERFACE
    "-Wl,--wrap=esp_log_write"
    "-Wl,--wrap=esp_log_writev"
    "-Wl,--undefined=__wrap_esp_log_write"
    "-Wl,--undefined=__wrap_esp_log_writev"
)

http server:

idf_component_register(
    SRCS "http_server.cpp"
    INCLUDE_DIRS "include"
    REQUIRES
        esp_wifi
        esp_netif
        nvs_flash
        esp_http_server
        espressif__mdns
        wifi_manager
        logging
    PRIV_REQUIRES espressif__arduino-esp32
)

drd handler:

idf_component_register(
    SRCS "drd_handler.cpp"
    INCLUDE_DIRS "include"
    REQUIRES
        app_update
        esp_timer
        esp_system 
        nvs_flash
)

captive dns:

idf_component_register(
    SRCS "captive_dns.cpp"
    INCLUDE_DIRS "include"
    REQUIRES
        lwip
        esp_netif
    PRIV_REQUIRES logging espressif__arduino-esp32
)

[fhrbata]

Hello @lbussy ,

thank you for the additional info. I cannot see any problem in your cmake files, but I also cannot see how else could this situation happen, unless the KCONFIG option for idf_component_register is used. Note it can be in whatever component that is part of the build. Just to rule out this possibility, here is a small patch, that IMHO fixes the problem I described.

diff --git a/tools/cmake/scripts/component_get_requirements.cmake b/tools/cmake/scripts/component_get_requirements.cmake
index bc94112e52ed..e6b3f69ab6d4 100644
--- a/tools/cmake/scripts/component_get_requirements.cmake
+++ b/tools/cmake/scripts/component_get_requirements.cmake
@@ -78,6 +78,14 @@ macro(idf_component_register)
     set(__component_kconfig_projbuild "${__KCONFIG_PROJBUILD}")
     set(__component_include_dirs "${__INCLUDE_DIRS}")
     set(__component_registered 1)
+
+    if(__component_kconfig)
+        get_filename_component(__component_kconfig "${__component_kconfig}" ABSOLUTE BASE_DIR "${CMAKE_CURRENT_LIST_DIR}")
+    endif()
+    if(__component_kconfig_projbuild)
+        get_filename_component(__component_kconfig_projbuild "${__component_kconfig_projbuild}" ABSOLUTE BASE_DIR "${CMAKE_CURRENT_LIST_DIR}")
+    endif()
+
     return()
 endmacro()
 

This is just my wild guess: If the cmake configuration passes with this patch, you can compare the build/kconfigs.in before and after this change to identify the component the build/Kconfig file belongs to. There of course can be other problem I'm not seeing, so my apologies if I'm completely off.

Thank you

[lbussy]

I see in the idf-diag output that your version is ESP-IDF v5.5.1-dirty

I believe that's because I downloaded the zip file rather than cloning the repo. I'll try to address that to rule it out.

Just to rule out this possibility, here is a small patch, that IMHO fixes the problem I described.

Acknowledged. I'm having a sh*t day at work, so it may be tomorrow before I can try this.