is the (case-preserved) name given to the find_package() call and _ROOT is literal. For example, find_package(Foo) will search prefixes specified in the Foo_ROOT CMake variable (if set). See policy CMP0074.
```
Second: I would expect to get a `NOT_FOUND` error in this case
Some of the required `COMPONENTS` are not found in `BOOST_ROOT`:
Tested with this `CMakeLists.txt`and `cmake v4.2.3`:
```cmake
cmake_minimum_required(VERSION 3.28...4.3 FATAL_ERROR)
# ---- Project ----
# Note: update this to your new project's name and version
project(Arcanelords VERSION 0.1 LANGUAGES CXX)
# ---- Include guards ----
if(PROJECT_SOURCE_DIR STREQUAL PROJECT_BINARY_DIR)
message(
FATAL_ERROR
"In-source builds not allowed. Please make a new directory (called a build directory) and run CMake from there."
)
endif()
list(APPEND CMAKE_MODULE_PATH "${CMAKE_CURRENT_LIST_DIR}/cmake")
include(AddUninstallTarget)
# Added in version 3.30. The FindBoost module is removed.
if(POLICY CMP0167)
cmake_policy(SET CMP0167 NEW)
endif()
set(Boost_VERBOSE ON)
set(Boost_DEBUG ON)
set(BOOST_ROOT $ENV{HOME}/.local)
set(BOOST_MIN_VERSION 1.90.0)
set(BOOST_REQUIRED_COMPONENTS program_options filesystem)
find_package(Boost ${BOOST_MIN_VERSION} REQUIRED EXACT COMPONENTS ${BOOST_REQUIRED_COMPONENTS})
```
I get this result:
```bash
-- Configuring incomplete, errors occurred!
bash-5.3$ cmake -S . -B build
-- Found Boost 1.90.0 at /Users/clausklein/.local/lib/cmake/Boost-1.90.0
-- Requested configuration: REQUIRED COMPONENTS program_options;filesystem
-- BoostConfig: find_package(boost_headers 1.90.0 EXACT CONFIG REQUIRED HINTS /Users/clausklein/.local/lib/cmake)
-- Found boost_headers 1.90.0 at /Users/clausklein/.local/lib/cmake/boost_headers-1.90.0
-- BoostConfig: find_package(boost_program_options 1.90.0 EXACT CONFIG REQUIRED HINTS /Users/clausklein/.local/lib/cmake)
-- Found boost_program_options 1.90.0 at /usr/local/lib/cmake/boost_program_options-1.90.0
-- Boost toolset is clang-darwin16 (AppleClang 16.0.0.16000026)
-- Scanning /usr/local/lib/cmake/boost_program_options-1.90.0/libboost_program_options-variant*.cmake
-- Including /usr/local/lib/cmake/boost_program_options-1.90.0/libboost_program_options-variant-shared.cmake
-- [x] libboost_program_options.dylib
-- Including /usr/local/lib/cmake/boost_program_options-1.90.0/libboost_program_options-variant-static.cmake
-- [] libboost_program_options.a
-- Adding boost_program_options dependencies: container;headers
-- Found boost_container 1.90.0 at /usr/local/lib/cmake/boost_container-1.90.0
-- Boost toolset is clang-darwin16 (AppleClang 16.0.0.16000026)
-- Scanning /usr/local/lib/cmake/boost_container-1.90.0/libboost_container-variant*.cmake
-- Including /usr/local/lib/cmake/boost_container-1.90.0/libboost_container-variant-shared.cmake
-- [x] libboost_container.dylib
-- Including /usr/local/lib/cmake/boost_container-1.90.0/libboost_container-variant-static.cmake
-- [] libboost_container.a
-- Adding boost_container dependencies: headers
-- Found boost_headers 1.90.0 at /Users/clausklein/.local/lib/cmake/boost_headers-1.90.0
-- Found boost_headers 1.90.0 at /Users/clausklein/.local/lib/cmake/boost_headers-1.90.0
-- BoostConfig: find_package(boost_filesystem 1.90.0 EXACT CONFIG REQUIRED HINTS /Users/clausklein/.local/lib/cmake)
-- Found boost_filesystem 1.90.0 at /usr/local/lib/cmake/boost_filesystem-1.90.0
-- Boost toolset is clang-darwin16 (AppleClang 16.0.0.16000026)
-- Scanning /usr/local/lib/cmake/boost_filesystem-1.90.0/libboost_filesystem-variant*.cmake
-- Including /usr/local/lib/cmake/boost_filesystem-1.90.0/libboost_filesystem-variant-shared.cmake
-- [x] libboost_filesystem.dylib
-- Including /usr/local/lib/cmake/boost_filesystem-1.90.0/libboost_filesystem-variant-static.cmake
-- [] libboost_filesystem.a
-- Adding boost_filesystem dependencies: atomic;headers
-- Found boost_atomic 1.90.0 at /usr/local/lib/cmake/boost_atomic-1.90.0
-- Boost toolset is clang-darwin16 (AppleClang 16.0.0.16000026)
-- Scanning /usr/local/lib/cmake/boost_atomic-1.90.0/libboost_atomic-variant*.cmake
-- Including /usr/local/lib/cmake/boost_atomic-1.90.0/libboost_atomic-variant-shared.cmake
-- [x] libboost_atomic.dylib
-- Including /usr/local/lib/cmake/boost_atomic-1.90.0/libboost_atomic-variant-static.cmake
-- [] libboost_atomic.a
-- Adding boost_atomic dependencies: headers
-- Found boost_headers 1.90.0 at /Users/clausklein/.local/lib/cmake/boost_headers-1.90.0
-- Found boost_headers 1.90.0 at /Users/clausklein/.local/lib/cmake/boost_headers-1.90.0
-- Configuring done (0.6s)
-- Generating done (0.0s)
-- Build files have been written to: /Users/clausklein/cmake/test/build
bash-5.3$
```
---
### Author:  [@rwan](https://discourse.cmake.org/u/rwan)
#### Post date: [March 9, 2026, 12:19pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/6 "2026-03-09T12:19:31Z")
Hi Craig,
Thank you for the follow-up! I’m using the default CMake for Ubuntu 25.10, which is CMake version 3.31.6 .
My installation has two `BoostConfig.cmake`:
- /usr/local/Boost\_1\_90\_0/tools/boost\_install/BoostConfig.cmake
- /usr/local/Boost\_1\_90\_0/tools/cmake/config/BoostConfig.cmake
I’m not sure which one I should use as they don’t seem identical.
Since Claus provided a minimum working example, I gave it a try with a few minor changes (i.e., removed “include (AddUninstallTarget)”). This is what I get (`/usr/local/boost` from my earlier message is a symbolic link to `/usr/local/Boost_1_90_0/`):
```bash
$ env | grep BOOST_ROOT
BOOST_ROOT=/usr/local/Boost_1_90_0
$ cmake ..
CMake Error at CMakeLists.txt:32 (find_package):
Could not find a configuration file for package “Boost” that exactly
matches requested version “1.90.0”.
The following configuration files were considered but not accepted:
/usr/lib/x86_64-linux-gnu/cmake/Boost-1.88.0/BoostConfig.cmake, version: 1.88.0
/lib/x86_64-linux-gnu/cmake/Boost-1.88.0/BoostConfig.cmake, version: 1.88.0
– Configuring incomplete, errors occurred!
```
With both `Boost_VERBOSE` and `Boost_DEBUG` turned ON, I was hoping it would print a message indicating that it tried searching in `BOOST_ROOT`. But, no…
If I change `BOOST_MIN_VERSION` to 1.88.0, then it works since it finds the system installed files (after having installed the Ubuntu “program\_options” and “filesystem” packages).
I just played around a bit more and changed `BOOST_MIN_VERSION` back to 1.90.0. Then, I changed the value of `BOOST_ROOT` by adding `tools` to the end (I naively thought maybe I could help it a bit…). And I got this:
```bash
$ export BOOST_ROOT=/usr/local/Boost_1_90_0/tools
$ cmake ..
CMake Error at CMakeLists.txt:32 (find_package):
Could not find a configuration file for package “Boost” that exactly
matches requested version “1.90.0”.
The following configuration files were considered but not accepted:
/usr/local/Boost_1_90_0/tools/boost_install/BoostConfig.cmake, version: unknown
/usr/lib/x86_64-linux-gnu/cmake/Boost-1.88.0/BoostConfig.cmake, version: 1.88.0
/lib/x86_64-linux-gnu/cmake/Boost-1.88.0/BoostConfig.cmake, version: 1.88.0
– Configuring incomplete, errors occurred!
```
So…it **is** accepting `BOOST_ROOT` but it’s not using it as I (we?) expect?
Maybe you can see something that I cannot… Thank you for your help!
Ray
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [March 9, 2026, 2:37pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/7 "2026-03-09T14:37:39Z")
It seems to me, you have downloaded the source file archive without cmake, that is not usable out of the box!
If you want to build boost yourself it only works like this:
```cmake
cmake_minimum_required(VERSION 3.30...4.3)
project(BoostExamples LANGUAGES CXX)
enable_testing()
# ---- Dependencies ----
if(PROJECT_IS_TOP_LEVEL)
include(../cmake/ccache.cmake)
set(CMAKE_SKIP_TEST_ALL_DEPENDENCY NO)
if(NOT DEFINED CMAKE_CXX_STANDARD)
set(CMAKE_CXX_STANDARD 20)
endif()
if(NOT DEFINED CMAKE_PREFIX_PATH)
list(APPEND CMAKE_PREFIX_PATH ../stagedir)
endif()
if(NOT DEFINED BOOST_USE_MODULES)
set(BOOST_USE_MODULES OFF)
endif()
if(BOOST_USE_MODULES)
set(CMAKE_CXX_SCAN_FOR_MODULES ON)
set(CMAKE_CXX_MODULE_STD OFF) # TODO(CK): not yet!
else()
set(CMAKE_CXX_SCAN_FOR_MODULES OFF)
endif()
block()
set(BOOST_DEBUG YES)
set(BOOST_VERBOSE YES)
list(APPEND BOOST_INCLUDE_LIBRARIES any asio regex test)
set(CMAKE_SKIP_INSTALL_RULES ON)
set(BUILD_SHARED_LIBS ON)
set(BOOST_SKIP_INSTALL_RULES ${CMAKE_SKIP_INSTALL_RULES})
set(BOOST_VERSION 1.90.0)
include(FetchContent)
FetchContent_Declare(
Boost
URL
https://github.com/boostorg/boost/releases/download/boost-${BOOST_VERSION}/boost-${BOOST_VERSION}-cmake.7z
URL_HASH
SHA256=218e74c4aa362a994b7b7a23b2920f455a00205c656405fcf262cf60b8871921
EXCLUDE_FROM_ALL
SYSTEM
FIND_PACKAGE_ARGS
${BOOST_VERSION}
COMPONENTS
any
asio
regex
unit_test_framework
)
FetchContent_MakeAvailable(Boost)
endblock()
endif()
```
You find my current version here [boost-cmake](https://github.com/ClausKlein/boost-cmake/pull/11) ; use if as you need.
The most important variable for you to set is `BOOST_INCLUDE_LIBRARIES`
---
### Author:  [@rwan](https://discourse.cmake.org/u/rwan)
#### Post date: [March 9, 2026, 5:22pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/8 "2026-03-09T17:22:11Z")
Hi Claus,
Thank you for the follow-up!
`/usr/local/boost/` has Boost downloaded from [Boost 1.90.0](https://www.boost.org/releases/latest/) and installed using the installation instructions ( [Boost Getting Started on Unix Variants](https://www.boost.org/doc/libs/latest/more/getting_started/unix-variants.html) ) – i.e., `./bootstrap.h` and `./b2`.
This cannot be used directly by CMake? I thought a C++ project configured using CMake could use it directly, just like other shared libraries on my system. (I have heard from others that Boost support in “CMake” is special and not straight-forward…I didn’t know why, but I guess I do now!)
Thank you for your advice and the sample code! I now know what I was trying wasn’t possible and the only way is what your code does.
Thank you!
Ray
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [March 9, 2026, 6:30pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/9 "2026-03-09T18:30:30Z")
Original boost [Easy Build and Install](https://www.boost.org/doc/libs/latest/more/getting_started/unix-variants.html#easy-build-and-install) works too, but you have to install it and not use the build tree!
My `boost-cmake` helps if you wand to build only a view boost libs and their dependentcies and install it from you own cmake project using `FetchContent`.
---
### Author:  [@rwan](https://discourse.cmake.org/u/rwan)
#### Post date: [March 10, 2026, 11:47am UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/10 "2026-03-10T11:47:56Z")
Hmmmm, I have done that “Easy Build and Install” installation according to those instructions (and not using the build tree), but maybe I have done something wrong. That `BoostConfig.cmake` really looks like it’s in the wrong place…
Let me take another look at what I’ve done on my system.
And yes, your `boost-cmake` is great; I have been using it since last year (when you helped me on the other thread, which I mentioned in my first message in this thread – thank you! 🙂 ). I just thought if a user (or me) installed Boost on the system, surely there must be a way to use it directly.
Anyway, I’ll look into how I have installed it on my system. Perhaps I did something wrong…
Thank you for your help!
Ray
---
### Author:  [@craig.scott](https://discourse.cmake.org/u/craig.scott)
#### Post date: [March 10, 2026, 9:10pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/11 "2026-03-10T21:10:29Z")
> [@ClausKlein](#):
>
> Some of the required `COMPONENTS` are not found in `BOOST_ROOT`:
Which components? I don’t see any failures in finding components in your example output.
---
### Author:  [@ClausKlein](https://discourse.cmake.org/u/ClausKlein)
#### Post date: [March 10, 2026, 9:14pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/12 "2026-03-10T21:14:16Z")
All are found, but not at BOOST\_ROOT:
/usr/local/lib/cmake/boost\_program\_options-1.90.0/libboost\_program\_options-variant-shared.cmake
/usr/local/lib/cmake/boost\_filesystem-1.90.0/libboost\_filesystem-variant-shared.cmake
---
### Author:  [@craig.scott](https://discourse.cmake.org/u/craig.scott)
#### Post date: [March 11, 2026, 11:44pm UTC](https://discourse.cmake.org/t/forcing-a-locally-installed-boost-to-be-used-instead-of-the-system-level-one/15549/13 "2026-03-11T23:44:01Z")
That’s probably to do with how Boost implemented their config package. It looks like they create separate packages for at least some components. I would have expected `${BOOST_ROOT}` to be pushed to the “root stack” and for those nested component packages to see `${BOOST_ROOT}` from there. Maybe that isn’t happening, or maybe there’s something else about the way their nested component packages are implemented that doesn’t work with that. Or perhaps only some of the components are installed under your `BOOST_ROOT` and the search for the nested component packages then continues on to search in other locations.