Model providing packages that wrap python appear to be incompatible with one another on the python side

[ablaom]

There have been issues in which the model providing packages that wrap python using PythonCall cannot successfully resolve a mutually compatible python environment. (It seems that PythonCall/CondaPkg do not provide for separate python environments for julia-python packages that are to be imported simultaneously. ) In that case calling update() will likely fail. The workaround is to skip those packages with update(skip=...) and then update each one separately, as in update("MLJScikitlearnInterface", manifest=false).

At time of writing, the effected packages are:

• MLJSckitlearnInterface
• OutlierDetectionPython
• CatBoost

[ablaom]

To reproduce the problem discussed here, activate and instantiate this Project and if you don't immediately encounter issues, try using CatBoost or using one of the other julia-python packages listed above. Here's what I'm seeing:

Error: 
  × failed to solve the conda requirements of 'default' 'osx-64'
  ╰─▶ Cannot solve the request because of: The following packages are
      incompatible
      ├─ pyod 2.* can be installed with any of the following options:
      │  └─ pyod 2.0.0 | 2.0.1 | 2.0.2 | 2.0.2 | 2.0.3 | 2.0.4 | 2.0.5 | 2.0.6
      | 2.0.6 | 2.0.7 would require
      │     └─ numba >=0.51, which can be installed with any of the following
      options:
      │        ├─ numba 0.62.1 would require
      │        │  └─ llvmlite >=0.45.1,<0.46.0a0, which can be installed with
      any of the following options:
      │        │     └─ llvmlite 0.45.1 | 0.45.1 would require
      │        │        └─ python >=3.12,<3.13.0a0, which can be installed
      with any of the following options:
      │        │           └─ python 3.12.3
      │        ├─ numba 0.62.0 | 0.62.1 would require
      │        │  └─ llvmlite >=0.45.0,<0.46.0a0, which can be installed with
      any of the following options:
      │        │     └─ llvmlite 0.45.0 would require
      │        │        └─ python >=3.12,<3.13.0a0, which can be installed
      with any of the following options:
      │        │           └─ python 3.12.3
      │        ├─ numba 0.61.0 | 0.61.2 | 0.61.2 would require
      │        │  └─ llvmlite >=0.44.0,<0.45.0a0, which can be installed with
      any of the following options:
      │        │     └─ llvmlite 0.44.0 would require
      │        │        └─ python >=3.12,<3.13.0a0, which can be installed
      with any of the following options:
      │        │           └─ python 3.12.3
      │        └─ numba 0.59.0 | 0.59.1 | 0.60.0 | 0.61.0 | 0.61.0 | 0.61.2 |
      0.61.2 | 0.61.2 | 0.62.0 | 0.62.1 | 0.62.1 | 0.62.1 would require
      │           └─ python >=3.12,<3.13.0a0, which can be installed with any
      of the following options:
      │              └─ python 3.12.3
      └─ python >=3.10,!=3.14.0,!=3.14.1,<4,3.13.* *cp* cannot be installed
      because there are no viable options:
         ├─ python 3.13.0 | 3.13.0 | 3.13.0 | 3.13.1 | 3.13.1 | 3.13.1 |
      3.13.1 | 3.13.1 | 3.13.2 | 3.13.2 | 3.13.3 | 3.13.3 | 3.13.5 | 3.13.5 |
      3.13.5 | 3.13.7 | 3.13.8 | 3.13.9 | 3.13.9 | 3.13.10 | 3.13.11 | 3.13.11
      | 3.13.12 would require
         │  ├─ libzlib >=1.3.1,<2.0a0, which cannot be installed because there
      are no viable options:
         │  │  └─ libzlib 1.3.1 | 1.3.1 | 1.3.1 | 1.3.2 would constrain
         │  │     └─ zlib ==1.3.1 *_0, which conflicts with any installable
      versions previously reported
         │  └─ python_abi 3.13.* *_cp313, which cannot be installed because
      there are no viable options:
         │     └─ python_abi 3.13 | 3.13 | 3.13 | 3.13 | 3.13 would constrain
         │        └─ python 3.13.* *_cpython, which conflicts with any
      installable versions previously reported
         └─ python 3.13.0 | 3.13.0 | 3.13.0 | 3.13.1 | 3.13.1 | 3.13.1 |
      3.13.1 | 3.13.1 | 3.13.2 | 3.13.2 | 3.13.3 | 3.13.3 | 3.13.5 | 3.13.5 |
      3.13.5 | 3.13.7 | 3.13.8 | 3.13.9 | 3.13.9 | 3.13.10 | 3.13.11 | 3.13.11
      | 3.13.12 would require
            ├─ libzlib >=1.3.1,<2.0a0, which cannot be installed because there
      are no viable options:
            └─ python_abi 3.13.* *_cp313t, which cannot be installed because
      there are no viable options:
               └─ python_abi 3.13 | 3.13 | 3.13 | 3.13 | 3.13 would constrain
                  └─ python 3.13.* *_cpython, which conflicts with any
      installable versions previously reported

julia> versioninfo()
Julia Version 1.12.5
Commit 5fe89b8ddc1 (2026-02-09 16:05 UTC)
Build Info:
  Official https://julialang.org release
Platform Info:
  OS: macOS (x86_64-apple-darwin24.0.0)
  CPU: 12 × Intel(R) Core(TM) i7-8850H CPU @ 2.60GHz
  WORD_SIZE: 64
  LLVM: libLLVM-18.1.7 (ORCJIT, skylake)
  GC: Built with stock GC
Threads: 12 default, 1 interactive, 12 GC (on 12 virtual cores)
Environment:
  JULIA_LTS_PATH = /Applications/Julia-1.10.app/Contents/Resources/julia/bin/julia
  JULIA_PATH = /Users/anthony/.juliaup/bin/julia
  JULIA_EGLOT_PATH = /Applications/Julia-1.7.app/Contents/Resources/julia/bin/julia
  JULIA_NUM_THREADS = 12
  DYLD_LIBRARY_PATH = /usr/local/homebrew/Cellar/libomp/9.0.1/lib/
  JULIA_NIGHTLY_PATH = /Applications/Julia-1.11.app/Contents/Resources/julia/bin/julia
  JULIA_PKG_SERVER = pumasai.juliahub.com

I also get an error if I try an environment that contains only the three julia-python packages.