Windows Miniconda installs with broken conda-libmamba-solver [Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified module could not be found.) ]

[tyeth]

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What happened?

Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified module could not be found.)

Conda Info

Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified module could not be found.)

(base) C:\Users\tyeth>conda info
Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified module could not be found.)

     active environment : base
    active env location : C:\dev\software\miniconda3
            shell level : 1
       user config file : C:\Users\tyeth\.condarc
 populated config files : C:\dev\software\miniconda3\.condarc
          conda version : 25.1.1
    conda-build version : not installed
         python version : 3.12.9.final.0
                 solver : libmamba (default)
       virtual packages : __archspec=1=skylake
                          __conda=25.1.1=0
                          __cuda=12.8=0
                          __win=10.0.22000=0
       base environment : C:\dev\software\miniconda3  (read only)
      conda av data dir : C:\dev\software\miniconda3\etc\conda
  conda av metadata url : None
           channel URLs : https://repo.anaconda.com/pkgs/main/win-64
                          https://repo.anaconda.com/pkgs/main/noarch
                          https://repo.anaconda.com/pkgs/r/win-64
                          https://repo.anaconda.com/pkgs/r/noarch
                          https://repo.anaconda.com/pkgs/msys2/win-64
                          https://repo.anaconda.com/pkgs/msys2/noarch
          package cache : C:\dev\software\miniconda3\pkgs
                          C:\Users\tyeth\.conda\pkgs
                          C:\Users\tyeth\AppData\Local\conda\conda\pkgs
       envs directories : C:\Users\tyeth\.conda\envs
                          C:\dev\software\miniconda3\envs
                          C:\Users\tyeth\AppData\Local\conda\conda\envs
               platform : win-64
             user-agent : conda/25.1.1 requests/2.32.3 CPython/3.12.9 Windows/11 Windows/10.0.22000 solver/libmamba aau/0.5.0 c/. s/.
          administrator : False
             netrc file : None
           offline mode : False

Conda Config

(base) C:\Users\tyeth>conda config --show-sources
Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified module could not be found.)
==> C:\dev\software\miniconda3\.condarc <==
channels:
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - https://repo.anaconda.com/pkgs/msys2

Conda list

(base) C:\Users\tyeth>conda list --show-channel-urls
Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified module could not be found.)
# packages in environment at C:\dev\software\miniconda3:
#
# Name                    Version                   Build  Channel
anaconda-anon-usage       0.5.0           py312hfc23b7f_100    defaults
anaconda_powershell_prompt 1.1.0                haa95532_0    defaults
anaconda_prompt           1.1.0                haa95532_0    defaults
annotated-types           0.6.0           py312haa95532_0    defaults
archspec                  0.2.3              pyhd3eb1b0_0    defaults
boltons                   24.1.0          py312haa95532_0    defaults
brotli-python             1.0.9           py312h5da7b33_9    defaults
bzip2                     1.0.8                h2bbff1b_6    defaults
ca-certificates           2024.12.31           haa95532_0    defaults
certifi                   2025.1.31       py312haa95532_0    defaults
cffi                      1.17.1          py312h827c3e9_1    defaults
charset-normalizer        3.3.2              pyhd3eb1b0_0    defaults
colorama                  0.4.6           py312haa95532_0    defaults
conda                     25.1.1          py312haa95532_0    defaults
conda-anaconda-telemetry  0.1.2           py312haa95532_0    defaults
conda-anaconda-tos        0.1.2           py312haa95532_0    defaults
conda-content-trust       0.2.0           py312haa95532_1    defaults
conda-libmamba-solver     25.1.1             pyhd3eb1b0_0    defaults
conda-package-handling    2.4.0           py312haa95532_0    defaults
conda-package-streaming   0.11.0          py312haa95532_0    defaults
cpp-expected              1.1.0                h214f63a_0    defaults
cryptography              43.0.3          py312hbd6ee87_1    defaults
distro                    1.9.0           py312haa95532_0    defaults
expat                     2.6.4                h8ddb27b_0    defaults
fmt                       9.1.0                h6d14046_1    defaults
frozendict                2.4.2           py312haa95532_0    defaults
idna                      3.7             py312haa95532_0    defaults
jsonpatch                 1.33            py312haa95532_1    defaults
jsonpointer               2.1                pyhd3eb1b0_0    defaults
libarchive                3.7.7                h9243413_0    defaults
libcurl                   8.11.1               haff574d_0    defaults
libffi                    3.4.4                hd77b12b_1    defaults
libiconv                  1.16                 h2bbff1b_3    defaults
libmamba                  2.0.5                hcd6fe79_1    defaults
libmambapy                2.0.5           py312h214f63a_1    defaults
libsolv                   0.7.30               hf2fb9eb_1    defaults
libssh2                   1.11.1               h2addb87_0    defaults
libxml2                   2.13.5               h24da03e_0    defaults
lz4-c                     1.9.4                h2bbff1b_1    defaults
markdown-it-py            2.2.0           py312haa95532_1    defaults
mdurl                     0.1.0           py312haa95532_0    defaults
menuinst                  2.2.0           py312h5da7b33_1    defaults
nlohmann_json             3.11.2               h6c2663c_0    defaults
openssl                   3.0.15               h827c3e9_0    defaults
packaging                 24.2            py312haa95532_0    defaults
pcre2                     10.42                h0ff8eda_1    defaults
pip                       25.0            py312haa95532_0    defaults
platformdirs              3.10.0          py312haa95532_0    defaults
pluggy                    1.5.0           py312haa95532_0    defaults
pybind11-abi              5                    hd3eb1b0_0    defaults
pycosat                   0.6.6           py312h827c3e9_2    defaults
pycparser                 2.21               pyhd3eb1b0_0    defaults
pydantic                  2.10.3          py312haa95532_0    defaults
pydantic-core             2.27.1          py312h636fa0f_0    defaults
pygments                  2.15.1          py312haa95532_1    defaults
pysocks                   1.7.1           py312haa95532_0    defaults
python                    3.12.9               h14ffc60_0    defaults
reproc                    14.2.4               hd77b12b_2    defaults
reproc-cpp                14.2.4               hd77b12b_2    defaults
requests                  2.32.3          py312haa95532_1    defaults
rich                      13.9.4          py312haa95532_0    defaults
ruamel.yaml               0.18.6          py312h827c3e9_0    defaults
ruamel.yaml.clib          0.2.8           py312h827c3e9_0    defaults
setuptools                75.8.0          py312haa95532_0    defaults
simdjson                  3.10.1               h214f63a_0    defaults
spdlog                    1.11.0               h59b6b97_0    defaults
sqlite                    3.45.3               h2bbff1b_0    defaults
tk                        8.6.14               h0416ee5_0    defaults
tqdm                      4.67.1          py312hfc267ef_0    defaults
truststore                0.10.0          py312haa95532_0    defaults
typing-extensions         4.12.2          py312haa95532_0    defaults
typing_extensions         4.12.2          py312haa95532_0    defaults
tzdata                    2025a                h04d1e81_0    defaults
urllib3                   2.3.0           py312haa95532_0    defaults
vc                        14.42                haa95532_4    defaults
vs2015_runtime            14.42.34433          he0abc0d_4    defaults
wheel                     0.45.1          py312haa95532_0    defaults
win_inet_pton             1.1.0           py312haa95532_0    defaults
xz                        5.4.6                h8cc25b3_1    defaults
yaml-cpp                  0.8.0                hd77b12b_1    defaults
zlib                      1.2.13               h8cc25b3_1    defaults
zstandard                 0.23.0          py312h4fc1ca9_1    defaults
zstd                      1.5.6                h8880b57_0    defaults

Additional Context

No response

[jaimergp]

Is this a permissions issue? Notice this line:

C:\dev\software\miniconda3  (read only)

Can you try installing it in a different location where you have permissions? Or give C:\dev\software\miniconda3 write permissions. That said, this might be more of a Miniconda installation problem, rather than a conda-libmamba-solver bug. Let me know what you find out.

[ZupoLlask]

@jaimergp No, because I'm getting exactly the same error (also similar setup) but my base environment status is writable.

I didn't change anything (regarding permissions or else) since my latest conda upgrade --all, except my previous conda upgrade --all run a few days ago.

I'm quite sure one of the upgraded packages was related with libmamba...

[ZupoLlask]

@tyeth I succeed in working this one around by running conda config --set solver classic, in spite of getting an error when running conda after that although without quitting.

Running conda upgrade --all resulted in libxml2 being downgraded from version 2.14.0 to 2.13.7 and that error is gone, even after setting solver back to libmamba and running conda again.

HOWEVER, with libxml2 version 2.13.7 in place, after setting solver back to libmamba, running conda upgrade --all will result in libxml2 upgrade to version 2.14.0 and after that conda is again broken (the same error shows up).

Re-running conda upgrade --all with classic solver shows no upgrade from libxml2 from version 2.13.7 to 2.14.0, and thus everything keeps working fine.

It really seems something is wrong between conda-libmamba-solver and libxml2 version 2.14.0, that doesn't break classic solver (in spite of it downgrades libxml2 to version 2.13.7).

[jaimergp]

I think that build of libxml2 2.14 was marked as broken so the faulty upgrade should not happen again.

[jaimergp]

Ah no, this is still needed: conda-forge/conda-forge-repodata-patches-feedstock#998

[ziyuang]

In my case, the error message still appears with libxml2==2.13.8, which cannot be fixed by setting conda config --set solver classic:

$ conda list
Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified procedure could not be found.)
Error while loading conda entry point: conda-libmamba-solver (DLL load failed while importing bindings: The specified procedure could not be found.)
# packages in environment at C:\Users\Ziyuan\miniforge3:
#
# Name                        Version          Build               Channel
archspec                      0.2.5            pyhd8ed1ab_0        conda-forge
boltons                       24.0.0           pypi_0              pypi
brotli                        1.1.0            pypi_0              pypi
bzip2                         1.0.8            h2466b09_7          conda-forge
ca-certificates               2025.6.15        h4c7d964_0          conda-forge
certifi                       2025.4.26        pypi_0              pypi
cffi                          1.17.1           py313ha7868ed_0     conda-forge
charset-normalizer            3.4.2            pyhd8ed1ab_0        conda-forge
colorama                      0.4.6            pyhd8ed1ab_1        conda-forge
conda                         25.3.0           pypi_0              pypi
conda-libmamba-solver         25.3.0           pypi_0              pypi
conda-package-handling        2.4.0            pyh7900ff3_2        conda-forge
conda-package-streaming       0.11.0           pyhd8ed1ab_1        conda-forge
cpp-expected                  1.1.0            hc790b64_1          conda-forge
distro                        1.9.0            pyhd8ed1ab_1        conda-forge
fmt                           11.1.4           h5f12afc_1          conda-forge
frozendict                    2.4.6            py313ha7868ed_0     conda-forge
h2                            4.2.0            pyhd8ed1ab_0        conda-forge
hpack                         4.1.0            pyhd8ed1ab_0        conda-forge
hyperframe                    6.1.0            pyhd8ed1ab_0        conda-forge
idna                          3.10             pyhd8ed1ab_1        conda-forge
jsonpatch                     1.33             pyhd8ed1ab_1        conda-forge
jsonpointer                   3.0.0            py313hfa70ccb_1     conda-forge
krb5                          1.21.3           hdf4eb48_0          conda-forge
libarchive                    3.8.1            gpl_h1ca5a36_100    conda-forge
libcurl                       8.14.1           h88aaa65_0          conda-forge
libexpat                      2.7.0            he0c23c2_0          conda-forge
libffi                        3.4.6            h537db12_1          conda-forge
libiconv                      1.18             h135ad9c_1          conda-forge
liblzma                       5.8.1            h2466b09_2          conda-forge
libmamba                      2.3.0            hd0d0357_1          conda-forge
libmambapy                    2.1.1            pypi_0              pypi
libmpdec                      4.0.0            h2466b09_0          conda-forge
libsolv                       0.7.33           hbb528cf_0          conda-forge
libsqlite                     3.50.2           hf5d6505_0          conda-forge
libssh2                       1.11.1           h9aa295b_0          conda-forge
libxml2                       2.13.8           h442d1da_0          conda-forge
libzlib                       1.3.1            h2466b09_2          conda-forge
lz4-c                         1.10.0           h2466b09_1          conda-forge
lzo                           2.10             hcfcfb64_1001       conda-forge
mamba                         2.3.0            hd7a1ebc_1          conda-forge
menuinst                      2.2.0            pypi_0              pypi
miniforge_console_shortcut    2.0              h57928b3_1          conda-forge
nlohmann_json                 3.11.3           he0c23c2_1          conda-forge
openssl                       3.5.1            h725018a_0          conda-forge
packaging                     25.0             pyh29332c3_1        conda-forge
pip                           25.1.1           pyh145f28c_0        conda-forge
platformdirs                  4.3.8            pyhe01879c_0        conda-forge
pluggy                        1.5.0            pypi_0              pypi
pybind11-abi                  4                hd8ed1ab_3          conda-forge
pycosat                       0.6.6            py313ha7868ed_2     conda-forge
pycparser                     2.22             pyh29332c3_1        conda-forge
pysocks                       1.7.1            pyh09c184e_7        conda-forge
python                        3.13.5           h7de537c_102_cp313  conda-forge
python_abi                    3.13             7_cp313             conda-forge
reproc                        14.2.5.post0     h2466b09_0          conda-forge
reproc-cpp                    14.2.5.post0     he0c23c2_0          conda-forge
requests                      2.32.3           pypi_0              pypi
ruamel-yaml                   0.18.10          pypi_0              pypi
ruamel.yaml                   0.18.14          py313ha7868ed_0     conda-forge
ruamel.yaml.clib              0.2.8            py313ha7868ed_1     conda-forge
setuptools                    80.1.0           pypi_0              pypi
simdjson                      3.13.0           hc790b64_0          conda-forge
tk                            8.6.13           h2c6b04d_2          conda-forge
tqdm                          4.67.1           pyhd8ed1ab_1        conda-forge
truststore                    0.10.1           pyh29332c3_0        conda-forge
tzdata                        2025b            h78e105d_0          conda-forge
ucrt                          10.0.22621.0     h57928b3_1          conda-forge
urllib3                       2.4.0            pypi_0              pypi
vc                            14.3             h2b53caa_26         conda-forge
vc14_runtime                  14.44.35208      h818238b_26         conda-forge
wheel                         0.45.1           pyhd8ed1ab_1        conda-forge
win_inet_pton                 1.1.0            pyh7428d3b_8        conda-forge
yaml-cpp                      0.8.0            he0c23c2_0          conda-forge
zstandard                     0.23.0           pypi_0              pypi
zstd                          1.5.7            hbeecb71_2          conda-forge

but mamba list works fine (I noticed mismatches in the channels)

$ mamba list
List of packages in environment: "C:\\Users\\my_name\\miniforge3"

  Name                        Version       Build               Channel
-----------------------------------------------------------------------------
  archspec                    0.2.5         pyhd8ed1ab_0        conda-forge
  boltons                     25.0.0        pyhd8ed1ab_0        conda-forge
  bzip2                       1.0.8         h2466b09_7          conda-forge
  ca-certificates             2025.6.15     h4c7d964_0          conda-forge
  certifi                     2025.6.15     pyhd8ed1ab_0        conda-forge
  cffi                        1.17.1        py313ha7868ed_0     conda-forge
  charset-normalizer          3.4.2         pyhd8ed1ab_0        conda-forge
  colorama                    0.4.6         pyhd8ed1ab_1        conda-forge
  conda                       25.5.1        py313hfa70ccb_0     conda-forge
  conda-libmamba-solver       25.4.0        pyhd8ed1ab_0        conda-forge
  conda-package-handling      2.4.0         pyh7900ff3_2        conda-forge
  conda-package-streaming     0.11.0        pyhd8ed1ab_1        conda-forge
  cpp-expected                1.1.0         hc790b64_1          conda-forge
  distro                      1.9.0         pyhd8ed1ab_1        conda-forge
  fmt                         11.1.4        h5f12afc_1          conda-forge
  frozendict                  2.4.6         py313ha7868ed_0     conda-forge
  h2                          4.2.0         pyhd8ed1ab_0        conda-forge
  hpack                       4.1.0         pyhd8ed1ab_0        conda-forge
  hyperframe                  6.1.0         pyhd8ed1ab_0        conda-forge
  idna                        3.10          pyhd8ed1ab_1        conda-forge
  jsonpatch                   1.33          pyhd8ed1ab_1        conda-forge
  jsonpointer                 3.0.0         py313hfa70ccb_1     conda-forge
  krb5                        1.21.3        hdf4eb48_0          conda-forge
  libarchive                  3.8.1         gpl_h1ca5a36_100    conda-forge
  libcurl                     8.14.1        h88aaa65_0          conda-forge
  libexpat                    2.7.0         he0c23c2_0          conda-forge
  libffi                      3.4.6         h537db12_1          conda-forge
  libiconv                    1.18          h135ad9c_1          conda-forge
  liblzma                     5.8.1         h2466b09_2          conda-forge
  libmamba                    2.3.0         hd0d0357_1          conda-forge
  libmambapy                  2.3.0         py313h85c7420_1     conda-forge
  libmpdec                    4.0.0         h2466b09_0          conda-forge
  libsolv                     0.7.33        hbb528cf_0          conda-forge
  libsqlite                   3.50.2        hf5d6505_0          conda-forge
  libssh2                     1.11.1        h9aa295b_0          conda-forge
  libxml2                     2.13.8        h442d1da_0          conda-forge
  libzlib                     1.3.1         h2466b09_2          conda-forge
  lz4-c                       1.10.0        h2466b09_1          conda-forge
  lzo                         2.10          hcfcfb64_1001       conda-forge
  mamba                       2.3.0         hd7a1ebc_1          conda-forge
  menuinst                    2.3.0         py313hfe59770_0     conda-forge
  miniforge_console_shortcut  2.0           h57928b3_1          conda-forge
  nlohmann_json               3.11.3        he0c23c2_1          conda-forge
  openssl                     3.5.1         h725018a_0          conda-forge
  packaging                   25.0          pyh29332c3_1        conda-forge
  pip                         25.1.1        pyh145f28c_0        conda-forge
  platformdirs                4.3.8         pyhe01879c_0        conda-forge
  pluggy                      1.6.0         pyhd8ed1ab_0        conda-forge
  pybind11-abi                4             hd8ed1ab_3          conda-forge
  pycosat                     0.6.6         py313ha7868ed_2     conda-forge
  pycparser                   2.22          pyh29332c3_1        conda-forge
  pysocks                     1.7.1         pyh09c184e_7        conda-forge
  python                      3.13.5        h7de537c_102_cp313  conda-forge
  python_abi                  3.13          7_cp313             conda-forge
  reproc                      14.2.5.post0  h2466b09_0          conda-forge
  reproc-cpp                  14.2.5.post0  he0c23c2_0          conda-forge
  requests                    2.32.4        pyhd8ed1ab_0        conda-forge
  ruamel.yaml                 0.18.14       py313ha7868ed_0     conda-forge
  ruamel.yaml.clib            0.2.8         py313ha7868ed_1     conda-forge
  setuptools                  80.9.0        pyhff2d567_0        conda-forge
  simdjson                    3.13.0        hc790b64_0          conda-forge
  tk                          8.6.13        h2c6b04d_2          conda-forge
  tqdm                        4.67.1        pyhd8ed1ab_1        conda-forge
  truststore                  0.10.1        pyh29332c3_0        conda-forge
  tzdata                      2025b         h78e105d_0          conda-forge
  ucrt                        10.0.22621.0  h57928b3_1          conda-forge
  urllib3                     2.5.0         pyhd8ed1ab_0        conda-forge
  vc                          14.3          h2b53caa_26         conda-forge
  vc14_runtime                14.44.35208   h818238b_26         conda-forge
  wheel                       0.45.1        pyhd8ed1ab_1        conda-forge
  win_inet_pton               1.1.0         pyh7428d3b_8        conda-forge
  yaml-cpp                    0.8.0         he0c23c2_0          conda-forge
  zstandard                   0.23.0        py313ha7868ed_2     conda-forge
  zstd                        1.5.7         hbeecb71_2          conda-forge