Python3 ImportError No module named ctypes when using Value from module multiprocessing

Question

I am using Ubuntu and have installed Python 2 7 5 and 3 4 0  In Python 2 7 5 I am able to successfully assign a variable x   Value  i   2   but not in 3 4 0  I am getting   Traceback  most recent call last      File   lt stdin gt    line 1  in  lt module gt     File   usr local lib python3 4 multiprocessing context py   line 132  in Value       from  sharedctypes import Value    File   usr local lib python3 4 multiprocessing sharedctypes py   line 10  in  lt  module gt     import ctypes    File   usr local lib python3 4 ctypes   init   py   line 7  in  lt module gt        from  ctypes import Union  Structure  Array ImportError  No module named   ctypes    I just updated to 3 3 2 through installing the source of 3 4 0  It installed in  usr local lib python3 4   Did I update to Python 3 4 correctly   One thing I noticed that Python 3 4 is installed in usr local lib  while Python 3 3 2 is still installed in usr lib  so it was not overwritten

User · Answer

I was having the same problem  None of the above solutions worked for me  The key challenge was that I didn t have the root access  So  I first download the source of libffi  Then I compiled it with usual commands    configure --prefix desired installation path to libffi make   Then I recompiled python using   configure --prefix  home user123 Softwares Python installation3   LDFLAGS  -L home user123 Softwares library libffi installation lib64  make  make install  In my case   home user123 Softwares library libffi installation lib64  is path to LIBFFI installation directory where libffi so is located  And   home user123 Softwares Python installation3  is path to Python installation directory  Modify them as per your case

User · Answer

If you are doing something nobody here will listen you about because  quot you re doing it the wrong way quot   but you have to do it  quot the wrong way quot  for reasons too asinine to explain and also beyond your ability to control  you can try this  Get libffi and install it into your user install area the usual way  git clone https   github com libffi libffi git cd libffi   configure --prefix path to your install root make make install  Then go back to your Python 3 source and find this part of the code in setup py at the top level of the python source directory         ffi inc    sysconfig get config var  quot LIBFFI INCLUDEDIR quot            if not ffi inc or ffi inc 0                     ffi inc   find file  ffi h       inc dirs          if ffi inc is not None              ffi h   ffi inc 0      ffi h              if not os path exists ffi h                   ffi inc   None                 print  Header file    does not exist  format ffi h           ffi lib   None         if ffi inc is not None              for lib name in   ffi    ffi pic                    if  self compiler find library file lib dirs  lib name                        ffi lib   lib name                     break          ffi lib  quot ffi quot     --- AND INSERT THIS LINE HERE THAT DOES NOT APPEAR ---         if ffi inc and ffi lib              ext include dirs extend ffi inc              ext libraries append ffi lib              self use system libffi   True  and add the line I have marked above with the comment  Why it is necessary  and why there is no way to get configure to respect  --without-system-ffi  on Linux platforms  perhaps I will find out why that is  quot unsupported quot  in the next couple of hours  but everything has worked ever since  Otherwise  best of luck    YMMV  WHAT IT DOES  just overrides the logic there and causes the compiler linking command to add  quot -lffi quot  which is all that it really needs  If you have the library user-installed  it is probably detecting the headers fine as long as your PKG CONFIG PATH includes path to your install root lib pkgconfig

User · Answer

Refer to this thread or this thread  for customized installation of libffi  it is difficult for Python3 7 to find the library location of libffi  An alternative method is to set the CONFIGURE LDFLAGS variable in the Makefile  for example CONFIGURE LDFLAGS  quot -L path to libffi-3 2 1 lib64 quot

User · Answer

On a fresh Debian image  cloning https   github com python cpython and running   sudo apt-get update sudo apt-get upgrade sudo apt-get dist-upgrade sudo apt-get install build-essential python-dev python-setuptools python-pip python-smbus sudo apt-get install libncursesw5-dev libgdbm-dev libc6-dev sudo apt-get install zlib1g-dev libsqlite3-dev tk-dev sudo apt-get install libssl-dev openssl sudo apt-get install libffi-dev   Now execute the configure file cloned above     configure make   alternatively  make -j 4  will utilize 4 threads sudo make altinstall   Got 3 7 installed and working for me   SLIGHT UPDATE  Looks like I said I would update this answer with some more explanation and two years later I don t have much to add    this SO post explains why certain libraries like python-dev might be necessary  this SO post explains why one might use the altinstall as opposed to install argument in the make command    Aside from that I guess the choice would be to either read through the cpython codebase looking for  include directives that need to be met  but what I usually do is keep trying to install the package and just keep reading through the output installing the required packages until it succeeds   Reminds me of the story of the Engineer  the Manager and the Programmer whose car rolls down a hill

User · Answer

None of the solution worked  You have to recompile your python again  once all the required packages were completely installed   Follow this    Install required packages  Run   configure --enable-optimizations   https   gist github com jerblack 798718c1910ccdd4ede92481229043be

User · Answer

Installing libffi-dev and re-installing python3 7 fixed the problem for me   to cleanly build py 3 7  libffi-dev  is required or else later stuff will fail  If using RHEL Fedora   yum install libffi-devel   or  sudo dnf install libffi-devel   If using Debian Ubuntu     sudo apt-get install libffi-dev

User · Answer

This solved the same error for me on Debian   sudo apt-get install libffi-dev   and compile again  Reference  issue31652

User · Answer

My solution  Installing libffi-dev with apt-get didn t help  But this helped  Installing libffi from source and then installing Python 3 8 from source   My configuration  Ubuntu 16 04 LTS Python 3 8 2  Step by step   I got the error message  ModuleNotFoundError  No module named   ctypes   when starting the debugger from Visual Studio Code  and when running python3 -c  import sklearn  sklearn show versions       download libffi v3 3 from https   github com libffi libffi releases install libtool  sudo apt-get install libtool The file README md from libffi mentions that autoconf and automake are also necessary  They were already installed on my system  configure libffi without docs       configure --disable-docs  make check  sudo make install   download python 3 8 from https   www python org downloads    configure make make test make install   After that my python installation could find  ctypes

User · Answer

Thought I d add the Centos installs   sudo yum -y install gcc gcc-c    sudo yum -y install zlib zlib-devel sudo yum -y install libffi-devel    Check python version   python3 -V  Create virtualenv   virtualenv -p python3 venv

User · Answer

You have to load the missing php3  Python3  modules from the package manager  If you have Ubuntu I recommend the Synaptic Package Manager   sudo apt-get install synaptic   There you can simply search for the missing modules  search for ctypes and install all the packages  Then go to your Python dir and do    configure make install    This should solve your problem

User · Answer

Detailed steps to install Python 3 7 in CentOS or any redhat linux machine     Download Python from https   www python org ftp python 3 7 0 Python-3 7 0 tar xz Extract the content in new folder Open Terminal in the same directory Run below code step by step      sudo yum -y install gcc gcc-c    sudo yum -y install zlib zlib-devel sudo yum -y install libffi-devel    configure make make install

User · Answer

If you use pyenv and get error  No module named   ctypes    like i am  on Debian Raspbian Ubuntu you need to run this commands   sudo apt-get install libffi-dev pyenv uninstall 3 7 6 pyenv install 3 7 6   Put your version of python instead of 3 7 6

User · Answer

How to install Python from source without libffi in  usr local   Download libffi from github and install to  path to local Download python source code and compile with the following configuration   export PKG CONFIG PATH  path to local lib pkgconfig   configure --prefix  path to python       LDFLAGS  -L path to local lib -Wl -R path to local lib        --enable-optimizations make make install

User · Answer

I run into this error when I tried to install Python 3 7 3 in Ubuntu 18 04 with next command    pyenv install 3 7 3  Installation succeeded after running   sudo apt-get update  amp  amp  sudo apt-get install libffi-dev  as suggested here   The issue was solved there

User · Answer

If you don t mind using Miniconda  the necessary external libraries and  ctypes are installed by default  It does take more space and may require using a moderately older version of Python  e g  3 7 6 instead of 3 8 2 as of this writing

[python] Python3: ImportError: No module named '_ctypes' when using Value from module multiprocessing

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