User Guide#

The conda-libmamba-solver plugin allows you to use libmamba, the same libsolv-powered solver used by mamba and micromamba, directly in conda.

How to install#

conda-libmamba-solver is distributed as a separate package, available on both conda-forge and defaults. The plugin needs to be present in the same environment you use conda from; most of the time, this is your base environment. Run this command:

$ conda install -n base conda-libmamba-solver

Update from the experimental versions (22.9 and below)#

The instructions in this page assume you are using conda-libmamba-solver 22.12 or above. Please refer to the v22.12.0 release notes for more details on how to update from a previous version if you were already using the experimental builds.


Even if installed, conda won’t use conda-libmamba-solver by default. It will still rely on the classic solver.

Try it once#

To enable it for one operation, you can use the --solver flag, available for conda create|install|remove|update commands.

$ conda install tensorflow --solver=libmamba


The --solver flag is also exposed as an environment variable, CONDA_SOLVER, in case you need that.

Set as default#

To enable it permanently, you can add solver: libmamba to your .condarc file, either manually, or with this command:

$ conda config --set solver libmamba

Revert to classic#

If you ever need to use the classic solver temporarily, you can again rely on the --solver flag:

$ conda install numpy --solver=classic

Finally, if you need to revert the default configuration back to classic, you can:

  • Run conda config --set solver classic (to do your choice explicit).

  • Run conda config --remove-key solver to delete the solver: libmamba line from your .condarc file.


If you are unsure what configuration is being used by conda, you can inspect it with conda config --show-sources.