#4263·mamba

Surprisingly hard environment specification to solve for `libsolv`

Author: jaimergpCreated May 7, 2026Updated Aug 4, 2026

Troubleshooting docs

My problem is not solved in the Troubleshooting docs

Anaconda default channels

I do NOT use the Anaconda default channels (pkgs/* etc.)

How did you install Mamba?

Micromamba

Search tried in issue tracker

hang

Latest version of Mamba

My problem is not solved with the latest version

Tried in Conda?

I have this problem with Conda as well, without using Mamba

Describe your issue

User reported solver hang in a conda-build recipe at #general > timeout of GHA CI runners?. This can be reproduced with both conda (using conda-libmamba-solver with libmamba 2.5.0 and libsolv 0.7.36) and micromamba 2.6.0.

This is the reproducer:

micromamba create -p $(mktemp -d) --dry-run "legend-pydataobj 1.17.4.*" "hist" "pip" "pyg4ometry" "scipy" "colorlog" "pandas" "particle" "python 3.10.*,>=3.10" "pygama" "legend-pygeom-hpges" "matplotlib-base" "hdf5plugin" "dbetto" "legend-pygeom-optics >=0.15.0" "numba >=0.60" "legend-pygeom-tools >=0.0.26" "numpy"

CPU is stuck at 100%, RAM is ballooning at 1.6-2.0GB. I then kill'd it via htop.

mamba info / micromamba info

bash

libmamba version : 2.6.0
     micromamba version : 2.6.0
           curl version : libcurl/8.20.0 OpenSSL/3.5.6 zlib/1.3.2 zstd/1.5.7 libssh2/1.11.1 nghttp2/1.68.1 mit-krb5/1.22.2
     libarchive version : libarchive 3.8.7 zlib/1.3.2 bz2lib/1.0.8 libzstd/1.5.7 CommonCrypto/system libb2/bundled
       envs directories : /Users/jrodriguez/.local/conda/envs
                          /Users/jrodriguez/.pixi/envs
          package cache : /Users/jrodriguez/.local/conda/pkgs
            environment : micromamba (active)
           env location : /Users/jrodriguez/.pixi/envs/micromamba
      user config files : /Users/jrodriguez/.mambarc
 populated config files : /Users/jrodriguez/.condarc
       virtual packages : __unix=0=0
                          __osx=26.4.1=0
                          __archspec=1=arm64
               channels : https://conda.anaconda.org/conda-forge/noarch
                          https://conda.anaconda.org/conda-forge/osx-arm64
       base environment : /Users/jrodriguez/.pixi
               platform : osx-arm64

Logs

bash

info     libmamba Loading site packages
info     libmamba parsing history: "/private/var/folders/s8/nlcyrbds38s81wf99b2kcmjr0000gn/T/tmp.xoznoTJzNO/conda-meta/history"
info     libmamba Searching index cache file for repo 'conda-forge/noarch'
info     libmamba Valid cache found  for 'conda-forge/noarch': 0
info     libmamba Searching index cache file for repo 'conda-forge/osx-arm64'
info     libmamba Valid cache found  for 'conda-forge/osx-arm64': 0
info     libmamba Using OpenSSL backend
info     libmamba Checking for CA certificates in the same prefix as the executable installation: "/Users/jrodriguez/.pixi/envs/micromamba/ssl/cert.pem"
info     libmamba Checking for CA certificates at the root prefix: "/Users/jrodriguez/.pixi/ssl/cert.pem"
info     libmamba Using system CA certificates at: /etc/ssl/cert.pem
Using Cached Shard Index for conda-forge/noarch                                                     ✔ Done
Using Cached Shard Index for conda-forge/osx-arm64                                                  ✔ Done
Fetching and Parsing Packages' Shards                                                     ✔ Done (0.5 sec)
info     libmamba Loaded subdir with shards: conda-forge/noarch
Using Cached Shard Index for conda-forge/noarch                                                     ✔ Done
Using Cached Shard Index for conda-forge/osx-arm64                                                  ✔ Done
Fetching and Parsing Packages' Shards                                                     ✔ Done (0.5 sec)
info     libmamba Loaded subdir with shards: conda-forge/noarch
info     libmamba Loading site packages

Resolving Environment                                                                     ✔ Done (0.7 sec)
info     libmamba Loading site packages
info     libmamba parsing history: "/private/var/folders/s8/nlcyrbds38s81wf99b2kcmjr0000gn/T/tmp.xoznoTJzNO/conda-meta/history"
info     libmamba Searching index cache file for repo 'conda-forge/noarch'
info     libmamba Valid cache found  for 'conda-forge/noarch': 0
info     libmamba Searching index cache file for repo 'conda-forge/osx-arm64'
info     libmamba Valid cache found  for 'conda-forge/osx-arm64': 0
Using Cached Shard Index for conda-forge/noarch                                                     ✔ Done
Using Cached Shard Index for conda-forge/osx-arm64                                                  ✔ Done
Fetching and Parsing Packages' Shards                                                     ✔ Done (0.7 sec)
info     libmamba Loaded subdir with shards: conda-forge/noarch
Using Cached Shard Index for conda-forge/noarch                                                     ✔ Done
Using Cached Shard Index for conda-forge/osx-arm64                                                  ✔ Done
Fetching and Parsing Packages' Shards                                                     ✔ Done (0.7 sec)
info     libmamba Loaded subdir with shards: conda-forge/noarch
info     libmamba Loading site packages

Resolving Environment                                                                           ⧖ Starting

environment.yml

yaml

~/.condarc

yaml

Source: mamba-org/mamba

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