05 June 2021

Nuitka Release 0.6.15

This is to inform you about the new stable release of Nuitka. It is the extremely compatible Python compiler, “download now”.

This release polished previous work with bug fixes, but there are also important new things that help make Nuitka more usable, with one important performance improvement.

Bug Fixes

  • Fix, hard imports were not automatically used in code generation leading to errors when used. Fixed in already.

  • Windows: Fix, clcache was disabled by mistake. Fixed in already.

  • Standalone: Added data files for jsonschema to be copied automatically.

  • Standalone: Support for pendulum wasn’t working anymore with the last release due to plugin interface issues.

  • Retry downloads without SSL if that fails, as some Python do not have working SSL. Fixed in already.

  • Fix, the ccache path wasn’t working if it contained spaces. Fixed in already.

  • Onefile: For Linux and ARM using proper download off appimage. Fixed in already.

  • Standalone: Added support for pyreadstat. Fixed in already.

  • Standalone: Added missing dependencies for pandas. Fixed in already.

  • Standalone: Some preloaded packages from .pth do not have a __path__, these can and must be ignored.

  • Onefile: On Linux, the sys.argv[0] was not the original file as advertised.

  • Standalone: Do not consider .mesh and .frag files as DLls in the Qt bindings when including the qml support. This was causing errors on Linux, but was generally wasteful.

  • Fix, project options could be injected twice, which could lead to errors with options that were only allowed once, e.g. --linux-onefile-icon.

  • Windows: When updating the resources in created binaries, treat all kinds of OSError with information output.

  • Onefile: Remove onefile target binary path at startup as well, so it cannot cause confusion after error exit.

  • Onefile: In case of error exit from AppImage, preserve its outputs and attempt to detect if there was a locking issue.

  • Standalone: Scan package folders on Linux for DLLs too. This is necessary to properly handle PyQt5 in case of Qt installed in the system as well.

  • Standalone: On Linux, standard QML files were not found.

  • Standalone: Enforce C locale when detecting DLLs on Linux, otherwise whitelisting messages didn’t work properly on newer Linux.

  • Standalone: Added support for tzdata package data files.

  • Standalone: Added support for exchangelib.

  • Python3.9: Fix, type subscripts could cause optimization errors.

  • UI: Project options didn’t properly handle quoting of arguments, these are normally removed by the shell.

  • Linux: The default icon for Python in the system is now found with more version specific names and should work on more systems.

  • Standalone: Do not include libstdc++ as it should come from the system rather.

New Features

  • Added plugin anti-bloat plugin, intended to fight bloat. For now it can make including certain modules an error, a warning, or force ImportError, e.g. --noinclude-setuptools-mode=nofollow is very much recommended to limit compilation size.

  • The pkg-resources builtin now covers metadata and importlib_metadata packages for compile time version resolution as well.

  • Added support for PySide2 on Python version before 3.6, because the patched code needs no workarounds. Fixed in already.

  • Windows: Convert images to icon files on the fly. So now you can specify multiple PNG files, and Nuitka will create an icon out of that automatically.

  • macOS: Automatically download ccache binary if not present.

  • Plugins: New interface to query the main script path. This allows plugins to look at its directory.

  • UI: Output the versions of Nuitka and Python during compilation.

  • UI: Added option to control static linking. So far this had been enabled only automatically for cases where we are certain, but this allows to force enable or disable it. Now an info is given, if Nuitka thinks it might be possible to enable it, but doesn’t do it automatically.

  • UI: Added --no-onefile to disable --onefile from project options.


  • Much enhanced GIL interaction with Python3.9 giving a big speed boost and better threading behaviour.

  • Faster conversion of iterables to list, if size can be know, allocation ahead saves a lot of effort.

  • Added support for GenericAlias objects as compile time constants.


  • Enhanced GitHub issue raising instructions.

  • Apply rstfmt to all documentation and make it part of the commit hook.

  • Make sure to check Scons files as well. This would have caught the code used to disable clcache temporarily.

  • Do not mention Travis in PR template anymore, we have stopped using it.

  • Updated requirements to latest versions.

  • Bump requirements for development to 3.7 at least, toosl like black do not work with 3.6 anymore.

  • Started work on Nuitka Python, a CPython fork intended for enhanced performance and standalone support with Nuitka.


  • Determine system prefix without virtualenv outside of Scons, such that plugins can share the code. There was duplication with the numpy plugin, and this will only be more complete using all approaches. This also removes a lot of noise from the scons file moving it to shared code.

  • The Qt plugins now collect QML files with cleaner code.


  • Nicer error message if a wrong search mode is given.

  • Windows: Added timeout for determining run time traces with dependency walker, sometimes this hangs.

  • Added test to cover the zip importer.

  • Making use of project options in onefile tests, making it easier to execute them manually.


For Windows, it’s now easier than ever to create an icon for your deployment, because you can use PNG files, and need not produce ICO files anymore, with Nuitka doing that for you.

The onefile for Linux had some more or less severe problems that got addressed, esp. also when it came to QML applications with PySide.

On the side, we are preparing to greatly improve the caching of Nuitka, starting with retaining modules that were demoted to bytecode. There are changes in this release, to support that, but it’s not yet complete. We expect that scalability will then be possible to improve even further.

Generally this is mostly a maintenance release, which outside of the threading performance improvement has very little to offer for faster execution, but that actually does a lot. Unfortunately right now it’s limited to 3.9, but some of the newer Python’s will also be supported in later releases.