`MatchSpec` package name must be case insensitive

[emlys]

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

version

Latest version of Mamba

• My problem is not solved with the latest version

Tried in Conda?

I didn't try

Describe your issue

A package version string that was valid in micromamba 2.3.1 and below no longer works in 2.3.2.

$ micromamba install "GDAL!=3.6.*,!=3.7.*"
conda-forge/noarch                                          Using cache
conda-forge/osx-64                                          Using cache

error    libmamba Could not solve for environment specs
    The following package could not be installed
    └─ GDAL !=3.6.*,!=3.7.* * does not exist (perhaps a typo or a missing channel).
critical libmamba Could not solve for environment specs

However versions of the package that satisfy the requirement are indeed available and can be installed with micromamba 2.3.1.

mamba info / micromamba info

libmamba version : 2.3.2
     micromamba version : 2.3.2
           curl version : libcurl/8.14.1 (OpenSSL/3.5.2) SecureTransport zlib/1.3.1 zstd/1.5.7 libssh2/1.11.1 nghttp2/1.64.0
     libarchive version : libarchive 3.8.1 zlib/1.3.1 bz2lib/1.0.8 libzstd/1.5.7 CommonCrypto/system libb2/bundled
       envs directories : /Users/emily/miniforge3/envs
          package cache : /Users/emily/miniforge3/pkgs
                          /Users/emily/.mamba/pkgs
            environment : micromamba-test (active)
           env location : /Users/emily/miniforge3/envs/micromamba-test
      user config files : /Users/emily/.mambarc
 populated config files : /Users/emily/miniforge3/.condarc
       virtual packages : __unix=0=0
                          __osx=13.2.1=0
                          __archspec=1=x86_64_v4
               channels : https://conda.anaconda.org/conda-forge/noarch
                          https://conda.anaconda.org/conda-forge/osx-64
       base environment : /Users/emily/miniforge3
               platform : osx-64

Logs

info     libmamba Searching index cache file for repo 'conda-forge/noarch'
info     libmamba Valid cache found  for 'conda-forge/noarch': 1
conda-forge/noarch                                          Using cache
info     libmamba Searching index cache file for repo 'conda-forge/osx-64'
info     libmamba Valid cache found  for 'conda-forge/osx-64': 1
conda-forge/osx-64                                          Using cache
info     libmamba Using macOS SecureTransport backend
info     libmamba Checking for CA certificates at the root prefix: "/Users/emily/miniforge3/ssl/cacert.pem"
info     libmamba Using CA certificates from `conda-forge::ca-certificates` installed in the root prefix (i.e "/Users/emily/miniforge3/ssl/cacert.pem")
info     libmamba Attempting to read libsolv solv file "/Users/emily/miniforge3/pkgs/cache/eb045dd1.solv" for repo https://conda.anaconda.org/conda-forge/noarch
info     libmamba Expecting solv metadata : {"etag":"\"db18930922e8c3cc7564fa1bfb9f2025\"","mod":"Wed, 10 Sep 2025 18:52:02 GMT","tool_version":"2.0_0.7.35","url":"https://conda.anaconda.org/conda-forge/noarch"}
info     libmamba Loaded solv metadata : {"etag":"\"db18930922e8c3cc7564fa1bfb9f2025\"","mod":"Wed, 10 Sep 2025 18:52:02 GMT","tool_version":"2.0_0.7.35","url":"https://conda.anaconda.org/conda-forge/noarch"}
info     libmamba Metadata from solv are valid, loading successful
info     libmamba Attempting to read libsolv solv file "/Users/emily/miniforge3/pkgs/cache/cfe2df73.solv" for repo https://conda.anaconda.org/conda-forge/osx-64
info     libmamba Expecting solv metadata : {"etag":"\"669eed8edafa8132fbc03dd9b654e111\"","mod":"Wed, 10 Sep 2025 18:52:55 GMT","tool_version":"2.0_0.7.35","url":"https://conda.anaconda.org/conda-forge/osx-64"}
info     libmamba Loaded solv metadata : {"etag":"\"669eed8edafa8132fbc03dd9b654e111\"","mod":"Wed, 10 Sep 2025 18:52:55 GMT","tool_version":"2.0_0.7.35","url":"https://conda.anaconda.org/conda-forge/osx-64"}
info     libmamba Metadata from solv are valid, loading successful
info     libmamba Loading single package record: "/Users/emily/miniforge3/envs/micromamba-test/conda-meta/libcxx-21.1.1-h3d58e20_0.json"
info     libmamba Loading single package record: "/Users/emily/miniforge3/envs/micromamba-test/conda-meta/micromamba-2.3.2-0.json"
info     libmamba Loading site packages

error    libmamba Could not solve for environment specs
    The following package could not be installed
    └─ GDAL !=3.6.*,!=3.7.* * does not exist (perhaps a typo or a missing channel).
critical libmamba Could not solve for environment specs

environment.yml

~/.condarc

[AntoinePrv]

I understand what is going on.

Mamba uses a two parser, historically the Libsolv one more integrated with the solver, and more and more a new one that is only enabled for complex MatchSpecs (like the one here).
The switching point was changed in 2.3.2.

Here the name of the package is gdal. The libsolv parser seem to be case insensitive, while the mamba one is not.

@emlys your immediate fix would be to use gdal!=3.6.*,!=3.7.* (lower case) since that is the name of the package.

[AntoinePrv]

Ping @jezdez @jaimergp to answer the question:

Should MatchSpec package name be case insensitive?

[jaimergp]

I think conda has been historically case insensitive. I'm planning to write this down as a CEP too so it's clear.

[emlys]

Thanks for the explanation. It seems reasonable to enforce case sensitivity, but I expect this affects some other packages too where the package name on PyPI is capitalized differently than on conda-forge.