The limited API is not currently supported in the free-threaded build

[wills721]

Describe the bug

Can anyone help me with what is going on here with my Python3.14t build and how to fix?

/home/will/Python-3.14.2/Include/Python.h:52:4: error: #error "The limited API is not currently supported in the free-threaded build"
52 | # error "The limited API is not currently supported in the free-threaded build"
| ^~~~~
In file included from /home/will/Python-3.14.2/Include/Python.h:82:
/home/will/Python-3.14.2/Include/object.h:158:5: error: unknown type name ‘PyMutex’
158 | PyMutex ob_mutex; // per-object lock
| ^~~~~~~
/home/will/Python-3.14.2/Include/object.h: In function ‘Py_SET_SIZE’:
/home/will/Python-3.14.2/Include/object.h:311:5: error: implicit declaration of function ‘_Py_atomic_store_ssize_relaxed’ [-Wimplicit-function-declaration]
311 | _Py_atomic_store_ssize_relaxed(&ob->ob_size, size);

Regression Issue

• Select this option if this issue appears to be a regression.

Expected Behavior

Compile successfully.

Current Behavior

Fails to compile

Reproduction Steps

Build python3.14 with the following configure options:

./configure --prefix=/usr/local --enable-optimizations --with-lto --disable-gil --disable-shared

Possible Solution

No response

Additional Information/Context

No response

aws-crt-python version used

latest

Python version used

3.14.2t

Operating System and version

Ubuntu 24

[wills721]

Happens also on the Python-3.15.0a3

[DmitriyMusatkin]

free-threaded builds are currently not officially supported for this package. We can take this as a feature request.
Disabling limited api (Py_LIMITED_API) during build might work in your case

[wills721]

You mean undefine it or does one of the configure options take it out?

[wills721]

This is what I get. No idea what the library gcc is though.....I mean I know what gcc is but cant seem to find libgcc anything

          Run Build Command(s):/snap/thio/x1/usr/bin/gmake -f Makefile cmTC_084cc/fast && /snap/thio/x1/usr/bin/gmake  -f CMakeFiles/cmTC_084cc.dir/build.make CMakeFiles/cmTC_084cc.dir/build
          gmake[1]: Entering directory '/tmp/pip-install-6e9zgnof/awscrt_15ee9c9932604939a44a3366df9ab051/build/temp.linux-aarch64-cpython-314t/deps/CMakeFiles/CMakeTmp'
          Building C object CMakeFiles/cmTC_084cc.dir/testCCompiler.c.o
          /snap/thio/x1/usr/bin/gcc   -U Py_LIMITED_API  -o CMakeFiles/cmTC_084cc.dir/testCCompiler.c.o -c /tmp/pip-install-6e9zgnof/awscrt_15ee9c9932604939a44a3366df9ab051/build/temp.linux-aarch64-cpython-314t/deps/CMakeFiles/CMakeTmp/testCCompiler.c
          Linking C executable cmTC_084cc
          /snap/thio/x1/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_084cc.dir/link.txt --verbose=1
          /snap/thio/x1/usr/bin/gcc -U Py_LIMITED_API  CMakeFiles/cmTC_084cc.dir/testCCompiler.c.o -o cmTC_084cc
          /snap/thio/x1/usr/bin/ld: cannot find -lgcc: No such file or directory
          /snap/thio/x1/usr/bin/ld: cannot find -lgcc: No such file or directory
          collect2: error: ld returned 1 exit status
          gmake[1]: *** [CMakeFiles/cmTC_084cc.dir/build.make:99: cmTC_084cc] Error 1
          gmake[1]: Leaving directory '/tmp/pip-install-6e9zgnof/awscrt_15ee9c9932604939a44a3366df9ab051/build/temp.linux-aarch64-cpython-314t/deps/CMakeFiles/CMakeTmp'
          gmake: *** [Makefile:127: cmTC_084cc/fast] Error 2

[DmitriyMusatkin]

so the problem is python 3.14 does not support limited build and no gil at the same time. they are aiming to fix that in 3.15.

can you try this out to see if it works for you? #715
still needs a bunch of work, but at least it seems to build fine

[wills721]

@DmitriyMusatkin How would I try this out exactly since it is not yet merged? Right now I simply pull down this version and build https://www.python.org/ftp/python/3.14.2/Python-3.14.2.tgz

[wills721]

Not even Python 3.13 works with --disable-gil due to awscrt. Pretty ridiculous after all this time. @DmitriyMusatkin

[yilei]

@DmitriyMusatkin Thanks for taking a look at this! #715 doesn't quite work, but I tested with #722 and I can build and install the Python 3.14 free-threaded wheel:

❯ python -m build
❯ python -m pip install dist/awscrt-1.0.0.dev0-cp314-cp314t-linux_x86_64.whl
❯ python
Python 3.14.0 free-threading build (main, Feb 24 2026, 00:07:27) [GCC 11.4.0] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import _awscrt
>>> _awscrt.sha256_new()
<capsule object "aws_hash" at 0x237e5175af0>

[TingDaoK]

% python -m pip install awscrt  
Collecting awscrt
  Downloading awscrt-0.32.0-cp314-cp314t-macosx_10_15_universal2.whl.metadata (8.5 kB)
Downloading awscrt-0.32.0-cp314-cp314t-macosx_10_15_universal2.whl (3.4 MB)
   ━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━ 3.4/3.4 MB 66.2 MB/s  0:00:00
Installing collected packages: awscrt
Successfully installed awscrt-0.32.0

[notice] A new release of pip is available: 25.3 -> 26.0.1
[notice] To update, run: pip install --upgrade pip
% python -VV                    
Python 3.14.3 free-threading build (main, Mar 23 2026, 13:59:30) [Clang 20.1.4 ]

The latest version@0.32.0 now fixed the free-thread build and provides the free-thread wheel. Thanks everyone for the input!