The make install step fails with this error:

Traceback (most recent call last):
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/ensurepip/__main__.py", line 4, in <module>
    ensurepip._main()
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/ensurepip/__init__.py", line 189, in _main
    default_pip=args.default_pip,
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/ensurepip/__init__.py", line 102, in bootstrap
    _run_pip(args + [p[0] for p in _PROJECTS], additional_paths)
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/ensurepip/__init__.py", line 27, in _run_pip
    import pip
  File "/tmp/tmpcg658x_c/pip-9.0.1-py2.py3-none-any.whl/pip/__init__.py", line 28, in <module>
  File "/tmp/tmpcg658x_c/pip-9.0.1-py2.py3-none-any.whl/pip/vcs/mercurial.py", line 9, in <module>
  File "/tmp/tmpcg658x_c/pip-9.0.1-py2.py3-none-any.whl/pip/download.py", line 36, in <module>
  File "/tmp/tmpcg658x_c/pip-9.0.1-py2.py3-none-any.whl/pip/utils/glibc.py", line 4, in <module>
  File "/home/dandan/Downloads/cpython-3.7.0a1/Lib/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ModuleNotFoundError: No module named '_ctypes'
Makefile:1080: recipe for target 'install' failed
make: *** [install] Error 1

Am I missing something?

I expect that the root cause is missing libffi(-dev[el]) on your system, preventing _ctypes from building, so your quick fix would be to install that and try again.

However, not having _ctypes shouldn't cause installation to fail.  Donald, is ctypes a hard requirement for pip to install itself?  If so, ensurepip as called by `make install` should either gracefully handle a lack of ctypes or be disabled when ctypes is not available.

Confirming that this is still failing with 3.7.0 released.

In <https://bugs.python.org/issue32401#msg308926> Chi-Hsuan suggests “configure --without-ensurepip” as a workaround.

> I expect that the root cause is missing libffi(-dev[el]) on your system

Yes, on my Ubuntu 18.04, `make` failed to compile _ctypes module.
After install libffi-dev, it was compiled successfully:

One more word, full necessary dependencies on my Ubuntu 18.04:
sudo apt-get install build-essential libsqlite3-dev sqlite3 bzip2 libbz2-dev zlib1g-dev libssl-dev openssl libgdbm-dev libgdbm-compat-dev liblzma-dev libreadline-dev libncursesw5-dev libffi-dev uuid-dev

Similar error on CentOS 7

ModuleNotFoundError: No module named '_ctypes'
 
Install --  yum install libffi-devel

Repeat:
./configure --enable-optimizations
make altinstall

Results:
Collecting setuptools
Collecting pip
Installing collected packages: setuptools, pip
Successfully installed pip-10.0.1 setuptools-39.0.1

NOTE: 
The error did not stop python3.7 from operating as noted on this page. 

# python3.7
Python 3.7.0 (default, Jul 16 2018, 11:25:12)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-28)] on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> print ("Hello Python")
Hello Python
>>>

I'm getting the same error   File "/usr/src/Python-3.7.0/Lib/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ModuleNotFoundError: No module named '_ctypes'
Makefile:1122: recipe for target 'install' failed
make: *** [install] Error 1
 
Linux Mint 19

Hi All,

Iam using centos 7. And as mentioned in this thread, though this error came, Iam able to go to python3.7 interpreter fine.

However, when i wanted to install pip, I get the same _ctype error as below.

So, I think, this needs to be resolved in order to use python3.7 in centos.

 File "get-pip.py", line 20651, in <module>
    main()
  File "get-pip.py", line 197, in main
    bootstrap(tmpdir=tmpdir)
  File "get-pip.py", line 82, in bootstrap
    import pip._internal
  File "/tmp/tmpu88jadkc/pip.zip/pip/_internal/__init__.py", line 42, in <module>
  File "/tmp/tmpu88jadkc/pip.zip/pip/_internal/cmdoptions.py", line 16, in <module>
  File "/tmp/tmpu88jadkc/pip.zip/pip/_internal/index.py", line 24, in <module>
  File "/tmp/tmpu88jadkc/pip.zip/pip/_internal/download.py", line 38, in <module>
  File "/tmp/tmpu88jadkc/pip.zip/pip/_internal/utils/glibc.py", line 3, in <module>
  File "/usr/local/lib/python3.7/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ModuleNotFoundError: No module named '_ctypes'


Looking for advice.

As mentioned before, this is due to missing libffi-devel on a Centos 7 system. Verified it as well on one of my systems.

Could you try again, but before just do a 'yum install libffi-devel'?

Maybe a warning could be added to the install output when it can't find libffi.

Linux Mint 19.1

sudo make altinstall

Traceback (most recent call last):
  File "/usr/src/Python-3.7.2/Lib/runpy.py", line 193, in _run_module_as_main
    "__main__", mod_spec)
  File "/usr/src/Python-3.7.2/Lib/runpy.py", line 85, in _run_code
    exec(code, run_globals)
  File "/usr/src/Python-3.7.2/Lib/ensurepip/__main__.py", line 5, in <module>
    sys.exit(ensurepip._main())
  File "/usr/src/Python-3.7.2/Lib/ensurepip/__init__.py", line 204, in _main
    default_pip=args.default_pip,
  File "/usr/src/Python-3.7.2/Lib/ensurepip/__init__.py", line 117, in _bootstrap
    return _run_pip(args + [p[0] for p in _PROJECTS], additional_paths)
  File "/usr/src/Python-3.7.2/Lib/ensurepip/__init__.py", line 27, in _run_pip
    import pip._internal
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/__init__.py", line 40, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/cli/autocompletion.py", line 8, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/cli/main_parser.py", line 12, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/commands/__init__.py", line 6, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/commands/completion.py", line 6, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/cli/base_command.py", line 18, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/download.py", line 38, in <module>
  File "/tmp/tmpc5nmmwk0/pip-18.1-py2.py3-none-any.whl/pip/_internal/utils/glibc.py", line 3, in <module>
  File "/usr/src/Python-3.7.2/Lib/ctypes/__init__.py", line 7, in <module>
    from _ctypes import Union, Structure, Array
ModuleNotFoundError: No module named '_ctypes'
Makefile:1140: recipe for target 'altinstall' failed
make: *** [altinstall] Error 1

In case this helps: I noticed this during the build:


*** WARNING: renaming "_ssl" since importing it failed: ld.so.1: python: fatal: libssl.so.1.1: open failed: No such file or directory
*** WARNING: renaming "_hashlib" since importing it failed: ld.so.1: python: fatal: libssl.so.1.1: open failed: No such file or directory
*** WARNING: renaming "_ctypes" since importing it failed: ld.so.1: python: fatal: libffi.so.6: open failed: No such file or directory

...

Following modules built successfully but were removed because they could not be imported:
_ctypes               _hashlib              _ssl               

In my case the reason was that libffi was installed under /opt/local, so the fix was:


./configure LDFLAGS='-L/opt/local/lib -R/opt/local/lib'

and rebuild

For other users I would recommend to inspect the build output for _ctypes related errors, I am not saying that the cause is the same

Installing libffi-dev worked for me.

Ubuntu 16.04 in a very bare naked setup.
Similar/same problem profile by message and other lines in the log.
Installed libffi6 and libffi-dev => worked.

Not sure if both were needed (or interdependent, 2nd to 1st).