# Windows configure error when using the command line: "The C/CXX compiler identification is unknown.."
**URL:** https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053
**Category:** Usage
**Created:** [September 8, 2021, 9:47am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053 "2021-09-08T09:47:50Z")
**Posts on this page:** 9
**Page:** 1
### Author:  [@StevenWang](https://discourse.cmake.org/u/StevenWang)
#### Post date: [September 8, 2021, 9:47am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/1 "2021-09-08T09:47:50Z")
I fail to use the command line to configure, reporting errors as “The C compiler identification is unknown and The CXX compiler identification is unknown”.
But for the same project, it is successful when using the cmake-gui. My cmake version is 3.20.4.
report information like:
Selecting Windows SDK version 10.0.19041.0 to target Windows 10.0.19042.
The C compiler identification is MSVC 19.16.27045.0
The CXX compiler identification is MSVC 19.16.27045.0
Detecting C compiler ABI info
Detecting C compiler ABI info - done
Check for working C compiler: D:/Program Files/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe - skipped
Detecting C compile features
Detecting C compile features - done
Detecting CXX compiler ABI info
Detecting CXX compiler ABI info - done
Check for working CXX compiler: D:/Program Files/Microsoft Visual Studio/2017/Community/VC/Tools/MSVC/14.16.27023/bin/Hostx86/x86/cl.exe - skipped
Detecting CXX compile features
Detecting CXX compile features - done
operation system is Windows-10.0.19042
Found OpenMP\_C: -openmp (found version “2.0”)
Found OpenMP\_CXX: -openmp (found version “2.0”)
Found OpenMP: TRUE (found version “2.0”)
Anyone could help? I don’t know why there is a difference in my vs2017 build and how to solve it in command-line way.
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### Author:  [@hsattler](https://discourse.cmake.org/u/hsattler)
#### Post date: [September 8, 2021, 12:05pm UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/2 "2021-09-08T12:05:58Z")
Guessing: The cmake-gui chooses the 32bit (host and target) version of the compiler. You choose the host=64bit version with CLI
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### Author:  [@fdk17](https://discourse.cmake.org/u/fdk17)
#### Post date: [September 8, 2021, 2:12pm UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/3 "2021-09-08T14:12:12Z")
When you use the GUI it appears to be using the Hostx86 tools not Hostx64. Did the command line version work when not specifying the toolset with `-T`.
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### Author:  [@StevenWang](https://discourse.cmake.org/u/StevenWang)
#### Post date: [September 9, 2021, 1:19am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/4 "2021-09-09T01:19:33Z")
It still has the same prompt error when removing the “-T” option.
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### Author:  [@StevenWang](https://discourse.cmake.org/u/StevenWang)
#### Post date: [September 9, 2021, 1:55am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/5 "2021-09-09T01:55:41Z")
I try to add the x86 compiler path “D:\Program Files\Microsoft Visual Studio\2017\Community\VC\Tools\MSVC\14.16.27023\bin\Hostx86\x86” to the system environment path, it still has the same error.
Actually, I don’t know how the cmake-gui works and why it chooses the x86/32bits option. And how it detects the complier information of:
The C compiler identification is MSVC 19.16.27045.0
The CXX compiler identification is MSVC 19.16.27045.0
I have local search results for the cl.exe as shown below…
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### Author:  [@ben.boeckel](https://discourse.cmake.org/u/ben.boeckel)
#### Post date: [September 9, 2021, 2:36am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/6 "2021-09-09T02:36:07Z")
Usually this means that something like the SDK isn’t installed. Does the toolchain work outside of CMake?
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### Author:  [@StevenWang](https://discourse.cmake.org/u/StevenWang)
#### Post date: [September 9, 2021, 3:13am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/7 "2021-09-09T03:13:06Z")
I tested a simple cpp file using the shell of MSVC tool, the cl build was successful.
While I try the cmake command in the same shell, it prompt the same error…
– Selecting Windows SDK version 10.0.19041.0 to target Windows 10.0.19042.
– The C compiler identification is unknown
– The CXX compiler identification is unknown
CMake Error at CMakeLists.txt:2 (project):
No CMAKE\_C\_COMPILER could be found.
CMake Error at CMakeLists.txt:2 (project):
No CMAKE\_CXX\_COMPILER could be found.
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### Author:  [@buildSystemPerson](https://discourse.cmake.org/u/buildSystemPerson)
#### Post date: [September 9, 2021, 8:20pm UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/8 "2021-09-09T20:20:25Z")
Hello @StevenWang we ended up finding a solution over on this [discourse](https://discourse.cmake.org/t/no-cmake-c-compiler-could-be-found-no-cmake-cxx-compiler-could-be-found/3948/17). Try temporarily minimizing your PATH variable to see if that helps as shown in that thread.
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### Author:  [@StevenWang](https://discourse.cmake.org/u/StevenWang)
#### Post date: [September 10, 2021, 1:31am UTC](https://discourse.cmake.org/t/windows-configure-error-when-using-the-command-line-the-c-cxx-compiler-identification-is-unknown/4053/9 "2021-09-10T01:31:25Z")
Yes, minimizing the PATH in temp can solve this CLI issue!
Thank you and everyone who helped me so much.