Releasing a Version

How to Prepare a Release

This file gives an overview of what is necessary to build binary releases for NumPy.

Current build and release info

The current info on building and releasing NumPy and SciPy is scattered in several places. It should be summarized in one place, updated, and where necessary described in more detail. The sections below list all places where useful info can be found.

Source tree

  • INSTALL.rst.txt


  • wiki

Supported platforms and versions

NEP 29 outlines which Python versions are supported; For the first half of 2020, this will be Python >= 3.6. We test NumPy against all these versions every time we merge code to master. Binary installers may be available for a subset of these versions (see below).


OS X versions >= 10.9 are supported, for Python version support see NEP 29. We build binary wheels for OSX that are compatible with Python, system Python, homebrew and macports - see this OSX wheel building summary for details.


We build 32- and 64-bit wheels on Windows. Windows 7, 8 and 10 are supported. We build NumPy using the mingw-w64 toolchain on Appveyor.


We build and ship manylinux1 wheels for NumPy. Many Linux distributions include their own binary builds of NumPy.

BSD / Solaris

No binaries are provided, but successful builds on Solaris and BSD have been reported.

Tool chain

We build all our wheels on cloud infrastructure - so this list of compilers is for information and debugging builds locally. See the .travis.yml and appveyor.yml scripts in the numpy wheels repo for the definitive source of the build recipes. Packages that are available using pip are noted.


The same gcc version is used as the one with which Python itself is built on each platform. At the moment this means:

  • OS X builds on travis currently use clang. It appears that binary wheels for OSX >= 10.6 can be safely built from the travis-ci OSX 10.9 VMs when building against the Python from the installers;

  • Windows builds use the mingw-w64 toolchain;

  • Manylinux1 wheels use the gcc provided on the Manylinux docker images.

You will need Cython for building the binaries. Cython compiles the .pyx files in the NumPy distribution to .c files.


All the wheels link to a version of OpenBLAS supplied via the openblas-libs repo. The shared object (or DLL) is shipped with in the wheel, renamed to prevent name collisions with other OpenBLAS shared objects that may exist in the filesystem.

Building source archives and wheels

You will need write permission for numpy-wheels in order to trigger wheel builds.

Building docs

Building the documents requires a number of latex .sty files. Install them all to avoid aggravation.

  • Sphinx (pip)

  • numpydoc (pip)

  • Matplotlib

  • Texlive (or MikTeX on Windows)

Uploading to PyPI

Generating author/pr lists

You will need a personal access token so that scripts can access the github NumPy repository.

  • gitpython (pip)

  • pygithub (pip)


Virtualenv is a very useful tool to keep several versions of packages around. It is also used in the Paver script to build the docs.

What is released


We currently support Python 3.6-3.8 on Windows, OSX, and Linux

  • Windows: 32-bit and 64-bit wheels built using Appveyor;

  • OSX: x64_86 OSX wheels built using travis-ci;

  • Linux: 32-bit and 64-bit Manylinux1 wheels built using travis-ci.

See the numpy wheels building repository for more detail.


  • Release Notes

  • Changelog

Source distribution

We build source releases in both .zip and .tar.gz formats.

Release process

Agree on a release schedule

A typical release schedule is one beta, two release candidates and a final release. It’s best to discuss the timing on the mailing list first, in order for people to get their commits in on time, get doc wiki edits merged, etc. After a date is set, create a new maintenance/x.y.z branch, add new empty release notes for the next version in the master branch and update the Trac Milestones.

Make sure current branch builds a package correctly

git clean -fxd
python bdist
python sdist

To actually build the binaries after everything is set up correctly, the script can be used. For details of the build process itself, it is best to read the script.


The following steps are repeated for the beta(s), release candidates(s) and the final release.

Check deprecations

Before the release branch is made, it should be checked that all deprecated code that should be removed is actually removed, and all new deprecations say in the docstring or deprecation warning at what version the code will be removed.

Check the C API version number

The C API version needs to be tracked in three places

  • numpy/core/

  • numpy/core/code_generators/cversions.txt

  • numpy/core/include/numpy/numpyconfig.h

There are three steps to the process.

  1. If the API has changed, increment the C_API_VERSION in The API is unchanged only if any code compiled against the current API will be backward compatible with the last released NumPy version. Any changes to C structures or additions to the public interface will make the new API not backward compatible.

  2. If the C_API_VERSION in the first step has changed, or if the hash of the API has changed, the cversions.txt file needs to be updated. To check the hash, run the script numpy/core/ and note the API hash that is printed. If that hash does not match the last hash in numpy/core/code_generators/cversions.txt the hash has changed. Using both the appropriate C_API_VERSION and hash, add a new entry to cversions.txt. If the API version was not changed, but the hash differs, you will need to comment out the previous entry for that API version. For instance, in NumPy 1.9 annotations were added, which changed the hash, but the API was the same as in 1.8. The hash serves as a check for API changes, but it is not definitive.

    If steps 1 and 2 are done correctly, compiling the release should not give a warning “API mismatch detect at the beginning of the build”.

  3. The numpy/core/include/numpy/numpyconfig.h will need a new NPY_X_Y_API_VERSION macro, where X and Y are the major and minor version numbers of the release. The value given to that macro only needs to be increased from the previous version if some of the functions or macros in the include files were deprecated.

The C ABI version number in numpy/core/ should only be updated for a major release.

Check the release notes

Use towncrier to build the release note and commit the changes. This will remove all the fragments from doc/release/upcoming_changes and add doc/release/<version>-note.rst. Note that currently towncrier must be installed from its master branch as the last release (19.2.0) is outdated.

towncrier –version “<version>” git commit -m”Create release note”

Check that the release notes are up-to-date.

Update the release notes with a Highlights section. Mention some of the following:

  • major new features

  • deprecated and removed features

  • supported Python versions

  • for SciPy, supported NumPy version(s)

  • outlook for the near future

Update the release status and create a release “tag”

Identify the commit hash of the release, e.g. 1b2e1d63ff.


git co 1b2e1d63ff # gives warning about detached head

First, change/check the following variables in depending on the release version:

RELEASE_NOTES = 'doc/release/1.7.0-notes.rst'
LOG_START = 'v1.6.0'
LOG_END = 'maintenance/1.7.x'

Do any other changes. When you are ready to release, do the following changes:

diff --git a/ b/
index b1f53e3..8b36dbe 100755
--- a/
+++ b/
@@ -57,7 +57,7 @@ PLATFORMS           = ["Windows", "Linux", "Solaris", "Mac OS-
 MAJOR               = 1
 MINOR               = 7
 MICRO               = 0
-ISRELEASED          = False
+ISRELEASED          = True
 VERSION             = '%d.%d.%drc1' % (MAJOR, MINOR, MICRO)

 # Return the git revision as a string

And make sure the VERSION variable is set properly.

Now you can make the release commit and tag. We recommend you don’t push the commit or tag immediately, just in case you need to do more cleanup. We prefer to defer the push of the tag until we’re confident this is the exact form of the released code (see: Push the release tag and commit):

git commit -s -m “REL: Release.” git tag -s <version>

The -s flag makes a PGP (usually GPG) signed tag. Please do sign the release tags.

The release tag should have the release number in the annotation (tag message). Unfortunately, the name of a tag can be changed without breaking the signature, the contents of the message cannot.

See: for a discussion of signing release tags, and for instructions on creating a GPG key if you do not have one.

To make your key more readily identifiable as you, consider sending your key to public keyservers, with a command such as:

gpg --send-keys <yourkeyid>

Update the version of the master branch

Increment the release number in Release candidates should have “rc1” (or “rc2”, “rcN”) appended to the X.Y.Z format.

Also create a new version hash in cversions.txt and a corresponding version define NPY_x_y_API_VERSION in numpyconfig.h

Trigger the wheel builds

See the MacPython/numpy wheels repository.

In that repository edit the files:

  • azure/posix.yml

  • azure/windows.yml.

In both cases, set the BUILD_COMMIT variable to the current release tag - e.g. v1.19.0:

$ gvim azure/posix.yml azure/windows.yml
$ git commit -a
$ git push upstream HEAD

Make sure that the release tag has been pushed.

Trigger a build by pushing a commit of your edits to the repository. Note that you can do this on a branch, but it must be pushed upstream to the MacPython/numpy-wheels repository to trigger uploads since only that repo has the appropriate tokens to allow uploads.

The wheels, once built, appear at

Make the release

Build the changelog and notes for upload with:

paver write_release

Build and archive documentation


cd doc/
make dist

to check that the documentation is in a buildable state. Then, after tagging, create an archive of the documentation in the numpy/doc repo:

# This checks out and adds (``git add``) the
# documentation to the checked out repo.
make merge-doc
# Now edit the ``index.html`` file in the repo to reflect the new content.
# If the documentation is for a non-patch release (e.g. 1.19 -> 1.20),
# make sure to update the ``stable`` symlink to point to the new directory.
ln -sfn <latest_stable_directory> stable
# Commit the changes
git -C build/merge commit -am "Add documentation for <version>"
# Push to numpy/doc repo
git -C build/merge push

Update PyPI

The wheels and source should be uploaded to PyPI.

You should upload the wheels first, and the source formats last, to make sure that pip users don’t accidentally get a source install when they were expecting a binary wheel.

You can do this automatically using the wheel-uploader script from Here is the recommended incantation for downloading all the Windows, Manylinux, OSX wheels and uploading to PyPI.

NPY_WHLS=~/wheelhouse   # local directory to cache wheel downloads
wheel-uploader -u $CDN_URL -w $NPY_WHLS -v -s -t win numpy 1.11.1rc1
wheel-uploader -u $CDN_URL -w warehouse -v -s -t macosx numpy 1.11.1rc1
wheel-uploader -u $CDN_URL -w warehouse -v -s -t manylinux1 numpy 1.11.1rc1

The -v flag gives verbose feedback, -s causes the script to sign the wheels with your GPG key before upload. Don’t forget to upload the wheels before the source tarball, so there is no period for which people switch from an expected binary install to a source install from PyPI.

There are two ways to update the source release on PyPI, the first one is:

$ git clean -fxd  # to be safe
$ python sdist --formats=gztar,zip  # to check
# python sdist --formats=gztar,zip upload --sign

This will ask for your key PGP passphrase, in order to sign the built source packages.

The second way is to upload the PKG_INFO file inside the sdist dir in the web interface of PyPI. The source tarball can also be uploaded through this interface.

Push the release tag and commit

Finally, now you are confident this tag correctly defines the source code that you released you can push the tag and release commit up to github:

git push  # Push release commit
git push upstream <version>  # Push tag named <version>

where upstream points to the main repository.


A release announcement with a link to the download site should be placed in the sidebar of the front page of

The should be a PR at The file that needs modification is www/index.rst. Search for News.

Announce to the lists

The release should be announced on the mailing lists of NumPy and SciPy, to python-announce, and possibly also those of Matplotlib, IPython and/or Pygame.

During the beta/RC phase, an explicit request for testing the binaries with several other libraries (SciPy/Matplotlib/Pygame) should be posted on the mailing list.

Announce to Linux Weekly News

Email the editor of LWN to let them know of the release. Directions at:

After the final release

After the final release is announced, a few administrative tasks are left to be done:

  • Forward port changes in the release branch to release notes and release scripts, if any, to master branch.

  • Update the Milestones in Trac.

Step-by-Step Directions

This file contains a walkthrough of the NumPy 1.19.0 release on Linux, modified for building on azure and uploading to The commands can be copied into the command line, but be sure to replace 1.19.0 by the correct version.

This should be read together with the general directions in releasing.

Release Preparation

Backport Pull Requests

Changes that have been marked for this release must be backported to the maintenance/1.19.x branch.

Update Release documentation

The file doc/changelog/1.19.0-changelog.rst should be updated to reflect the final list of changes and contributors. This text can be generated by:

$ python tools/ $GITHUB v1.18.0..maintenance/1.19.x > doc/changelog/1.19.0-changelog.rst

where GITHUB contains your github access token. This text may also be appended to doc/release/1.19.0-notes.rst for patch release, though not for new releases like 1.19.0, as the changelogs for *.0 releases tend to be excessively long. The doc/source/release.rst file should also be updated with a link to the new release notes. These changes should be committed to the maintenance branch, and later will be forward ported to master. The changelog should be reviewed for name duplicates or short names and the .mailmap file updated if needed.

Finish the Release Note

Fill out the release note doc/release/1.19.0-notes.rst calling out significant changes.

Release Walkthrough

Note that in the code snippets below, upstream refers to the root repository on github and origin to a fork in your personal account. You may need to make adjustments if you have not forked the repository but simply cloned it locally. You can also edit .git/config and add upstream if it isn’t already present.

Prepare the release commit

Checkout the branch for the release, make sure it is up to date, and clean the repository:

$ git checkout maintenance/1.19.x
$ git pull upstream maintenance/1.19.x
$ git submodule update
$ git clean -xdfq

Edit and as detailed in HOWTO_RELEASE:

$ gvim  # Generally only needs updating
$ git commit -a -m"REL: NumPy 1.19.0 release."

Sanity check:

$ python3 -m "full"

Push this release directly onto the end of the maintenance branch. This requires write permission to the numpy repository:

$ git push upstream HEAD

Build source releases

Paver is used to build the source releases. It will create the release and release/installers directories and put the *.zip and *.tar.gz source releases in the latter.

$ python3 -m cython --version  # check for correct cython version
$ paver sdist  # sdist will do a git clean -xdfq, so we omit that

Build wheels

Trigger the wheels build by pointing the numpy-wheels repository at this commit. This can take up to an hour. The numpy-wheels repository is cloned from If this is the first release in a series, start with a pull as the repo may have been accessed and changed by someone else, then create a new branch for the series. If the branch already exists skip this:

$ cd ../numpy-wheels
$ git co master
$ git pull upstream master
$ git branch v1.19.x

Checkout the new branch and edit the azure-pipelines.yml and .travis.yml files to make sure they have the correct version, and put in the commit hash for the REL commit created above for BUILD_COMMIT. The azure/posix.yml and .travis.yml files may also need the Cython versions updated to keep up with Python releases, but generally just do:

$ git checkout v1.19.x
$ gvim azure-pipelines .travis.yml
$ git commit -a -m"NumPy 1.19.0 release."
$ git push upstream HEAD

Now wait. If you get nervous at the amount of time taken – the builds can take a while – you can check the build progress by following the links provided at to check the build status. Check if all the needed wheels have been built and uploaded to the staging repository before proceeding.

Note that sometimes builds, like tests, fail for unrelated reasons and you will need to rerun them. You will need to be logged in under ‘numpy’ to do this on azure.

Download wheels

When the wheels have all been successfully built and staged, download them from the Anaconda staging directory using the tools/ script:

$ cd ../numpy
$ python3 tools/ 1.19.0

Generate the README files

This needs to be done after all installers are downloaded, but before the pavement file is updated for continued development:

$ paver write_release

Tag the release

Once the wheels have been built and downloaded without errors tag the REL commit, signing it with your gpg key:

$ git tag -s -m"NumPy 1.19.0 release" v1.19.0

You should upload your public gpg key to github, so that the tag will appear “verified” there.

Check that the files in release/installers have the correct versions, then push the tag upstream:

$ git push upstream v1.19.0

We wait until this point to push the tag because it is public and should not be changed after it has been pushed.

Reset the maintenance branch into a development state

Add another REL commit to the numpy maintenance branch, which resets the ISREALEASED flag to False and increments the version counter:

$ gvim

Create release notes for next release and edit them to set the version:

$ cp doc/source/release/template.rst doc/source/release/1.19.1-notes.rst
$ gvim doc/source/release/1.19.1-notes.rst
$ git add doc/source/release/1.19.1-notes.rst

Add new release notes to the documentation release list:

$ gvim doc/source/release.rst

Commit the result:

$ git commit -a -m"REL: prepare 1.19.x for further development"
$ git push upstream HEAD

Upload to PyPI

Upload to PyPI using twine. A recent version of twine of is needed after recent PyPI changes, version 3.1.1 was used here:

$ cd ../numpy
$ twine upload release/installers/*.whl
$ twine upload release/installers/  # Upload last.

If one of the commands breaks in the middle, you may need to selectively upload the remaining files because PyPI does not allow the same file to be uploaded twice. The source file should be uploaded last to avoid synchronization problems that might occur if pip users access the files while this is in process. Note that PyPI only allows a single source distribution, here we have chosen the zip archive.

Upload files to github

Go to, there should be a v1.19.0 tag, click on it and hit the edit button for that tag. There are two ways to add files, using an editable text window and as binary uploads. Cut and paste the release/ file contents into the text window. You will probably need to make some edits to get it to look right. Then

  • Upload release/installers/numpy-1.19.0.tar.gz as a binary file.

  • Upload release/installers/ as a binary file.

  • Upload release/README.rst as a binary file.

  • Upload doc/changelog/1.19.0-changelog.rst as a binary file.

  • Check the pre-release button if this is a pre-releases.

  • Hit the {Publish,Update} release button at the bottom.

Upload documents to

This step is only needed for final releases and can be skipped for pre-releases. make merge-doc clones the numpy/doc repo into doc/build/merge and updates it with the new documentation:

$ pushd doc
$ make dist
$ make merge-doc
$ popd

If the release series is a new one, you will need to add a new section to the doc/build/merge/index.html front page just after the “insert here” comment:

$ gvim doc/build/merge/index.html +/'insert here'

Otherwise, only the zip and pdf links should be updated with the new tag name:

$ gvim doc/build/merge/index.html +/'tag v1.19'

You can “test run” the new documentation in a browser to make sure the links work:

$ firefox doc/build/merge/index.html

Once everything seems satisfactory, commit and upload the changes:

$ pushd doc/build/merge
$ git commit -am"Add documentation for v1.19.0"
$ git push
$ popd

Announce the release on

This assumes that you have forked

$ cd ../
$ git checkout master
$ git pull upstream master
$ git checkout -b numpy-1.19.0
$ gvim www/index.rst # edit the News section
$ git commit -a
$ git push origin HEAD

Now go to your fork and make a pull request for the branch.

Announce to mailing lists

The release should be announced on the numpy-discussion, scipy-devel, scipy-user, and python-announce-list mailing lists. Look at previous announcements for the basic template. The contributor and PR lists are the same as generated for the release notes above. If you crosspost, make sure that python-announce-list is BCC so that replies will not be sent to that list.

Post-Release Tasks

Checkout master and forward port the documentation changes:

$ git checkout -b post-1.19.0-release-update
$ git checkout maintenance/1.19.x doc/source/release/1.19.0-notes.rst
$ git checkout maintenance/1.19.x doc/changelog/1.19.0-changelog.rst
$ git checkout maintenance/1.19.x .mailmap  # only if updated for release.
$ gvim doc/source/release.rst  # Add link to new notes
$ git add doc/changelog/1.19.0-changelog.rst doc/source/release/1.19.0-notes.rst
$ git status  # check status before commit
$ git commit -a -m"REL: Update master after 1.19.0 release."
$ git push origin HEAD

Go to github and make a PR.