Environment solving error while installing pyfftw in Conda on Ubuntu

Question

I am trying to install pyfftw in a Conda environment from the condo-forge channel. I get the following output:

conda install -c conda-forge pyfftw

Output:

Channels:
 - conda-forge
 - defaults
Platform: linux-64
Collecting package metadata (repodata.json): done
Solving environment: \ warning  libmamba Added empty dependency for problem type SOLVER_RULE_UPDATE
failed

LibMambaUnsatisfiableError: Encountered problems while solving:
  - package _openmp_mutex-5.1-1_gnu requires _libgcc_mutex 0.1 main, but none of the providers can be installed

Could not solve for environment specs
The following packages are incompatible
├─ _openmp_mutex 5.1.*  is installable and it requires
│  └─ _libgcc_mutex 0.1 main, which can be installed;
├─ pin-1 is installable and it requires
│  └─ python 3.11.* , which can be installed;
└─ pyfftw is not installable because there are no viable options
   ├─ pyfftw [0.10.1|0.10.3|...|0.12.0] would require
   │  └─ python [2.7* |>=2.7,<2.8.0a0 ], which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.10.1|0.10.3|0.10.4] would require
   │  └─ python 3.4* , which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.10.1|0.10.3|0.10.4] would require
   │  └─ python [3.5* |>=3.5,<3.6.0a0 ], which conflicts with any installable versions previously reported;
   ├─ pyfftw 0.10.4 would require
   │  └─ python 3.6* , which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.10.4|0.11.0|0.11.1|0.12.0] would require
   │  └─ python >=3.6,<3.7.0a0 , which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.10.4|0.11.0|0.11.1|0.12.0|0.13.0] would require
   │  └─ python >=3.7,<3.8.0a0 , which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.11.1|0.12.0|0.13.0|0.13.1] would require
   │  └─ python >=3.8,<3.9.0a0 , which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.12.0|0.13.0|0.13.1] would require
   │  └─ python >=3.10,<3.11.0a0 , which conflicts with any installable versions previously reported;
   ├─ pyfftw [0.12.0|0.13.0|0.13.1] would require
   │  └─ python >=3.9,<3.10.0a0 , which conflicts with any installable versions previously reported;
   └─ pyfftw [0.13.0|0.13.1] would require
      └─ libgcc-ng >=12 , which requires
         └─ _libgcc_mutex 0.1 conda_forge, which conflicts with any installable versions previously reported.

Pins seem to be involved in the conflict. Currently pinned specs:
 - python 3.11.* (labeled as 'pin-1')

I do not understand the error. Does it mean we need three different Python versions?

What could be a solution to this?

I tried installing conda-libmamba-solver, but without success. The OS is Ubuntu 20.04 LTS.

Answer 1

Conda Forge has known issues with mixing packages with defaults channel (i.e., Anaconda). Try installing a fresh environment where everything comes from Conda Forge.

conda create -n foo -c conda-forge python=3.11 pyfftw

This solves for me without any issues.