vs2015 to vs2017 Transition

We are formally deprecating vs2015 in two weeks on 2020-04-07 and will move to vs2017. This change will enable us to support the usage of msbuild on Azure for the win platform and will provide additional support for C++. Most packages built with vs2015 can be linked with vs2017 toolchain (but not vice-versa). An exception is static libraries compiled with whole program optimization (/GL flag) which may be incompatible with the vs2017 toolchain. These static libraries will need to be rebuilt using vs2017.


Appveyor Deprecation

We are now starting to formally deprecate Appveyor in favor of Azure for builds on the win platform. Note that we have not been adding appveyor to new feedstocks for a while, so this is not a completely new change in policy. We will now, however, begin to actively disable Appveyor builds on feedstocks not using it by turning off builds for GitHub push events. Additionally, we have been issuing PRs to any remaining feedstocks to move them to Azure. We are aware that some packages built with msbuild cannot yet be moved to Azure and so are leaving Appveyor on for those feedstocks for now.


Python 2.7 Admin Command Available

A webservices admin command is now available to add Python 2.7 back to feedstocks. Put @conda-forge-admin add python 2.7 in the title on an issue in your feedstock. The admin webservices bot will then issue a PR adding back Python 2.7. Note that this PR will remove other Python builds and any win, aarch64, or ppc64le builds. If you want to keep those, merge the PR into a separate branch on your feedstock.


Python 2.7 and vs2008 Deprecation

  • Python 2.7 is no longer supported by the upstream developers as of 2020-01-01. Conda-forge is thus deprecating its Python 2.7 support. Conda-forge will provide no ongoing support for Python 2.7 builds and any existing builds are provided on an “as-is” basis.

  • A cf202003 label has been applied to the conda-forge channel for those who need a reference to the package index with Python 2.7.

  • We are removing support for vs2008 on Windows conjunction with the deprecation of Python 2.7, as it was only supported to build this version of Python.

  • We will provide an admin command that will add back Python 2.7 to any feedstock. Note that as stated above, we cannot provide support for any Python 2.7 builds generated with this admin command. Further, this admin command will only work on osx-64 and linux-64 platforms.



Clang 9.0.0 and gfortran 7.3.0 as default compilers in OSX.

  • If you maintain a feedstock which require a C/C++ compiler, no changes necessary. A rerender should be done next time the feedstock is updated to use the new compiler.

  • If you maintain a feedstock with a Fortran compiler, a PR to upgrade to gfortran 7.3.0 was already issued. If that PR was merged, there’s nothing to do. If not, contact core if you need help migrating.


We overhauled the blas support in conda-forge.

  • Our packages now build against NETLIB’s reference implementation.

  • You as a user can now choose the implementation available at runtime.

For more information please refer to the documentation.


It has happened! Conda-forge has migrated to the latest compilers 🎉.

If you:
  • maintain a compiled feedstock, it will likely need to be rerender

  • need to roll back to the old compilers, you can use the “cf201901” label



The rebuild is moving along nicely with almost a third of packages completed.

Recently completed are numpy and openblas which should open up much of the python numeric stack. We’re only about 5 feedstocks away from opening up all of R as well.


A minimal python 3.7 build is now available across all platforms and both compilers!


Deprecation notice for Python 3.5

As we start building out more of the python 3.7 stack, we will no longer be building python 3.5 packages.

No new python 3.5 packages will be built after 2018-10-01.


The compiler migration is in full swing. The bot will be making the rounds and modernizing more than 4000 packages. This is going to take a few months to get done so bear with us.


Conda forge now has a magical status bar for tracking the progress of migrations.

You can find this at