Non-default solver backend (libmamba)

Product Help
1

How do I fix this:
(base) murraycantor@Mac-mini ~ % conda create --name myenv10 python=3.10
Error while loading conda entry point: conda-libmamba-solver (dlopen(/Users/murraycantor/opt/anaconda3/lib/python3.9/site-packages/libmambapy/bindings.cpython-39-darwin.so, 0x0002): Library not loaded: @rpath/libarchive.19.dylib
Referenced from: <2FB9B657-7481-3BB3-9E09-387CC7C0B13E> /Users/murraycantor/opt/anaconda3/lib/libmamba.2.0.0.dylib
Reason: tried: ‘/Users/murraycantor/opt/anaconda3/lib/libarchive.19.dylib’ (no such file), ‘/Users/murraycantor/opt/anaconda3/lib/python3.9/site-packages/libmambapy/…/…/…/libarchive.19.dylib’ (no such file), ‘/Users/murraycantor/opt/anaconda3/lib/python3.9/site-packages/libmambapy/…/…/…/libarchive.19.dylib’ (no such file), ‘/Users/murraycantor/opt/anaconda3/bin/…/lib/libarchive.19.dylib’ (no such file), ‘/Users/murraycantor/opt/anaconda3/bin/…/lib/libarchive.19.dylib’ (no such file), ‘/usr/local/lib/libarchive.19.dylib’ (no such file), ‘/usr/lib/libarchive.19.dylib’ (no such file, not in dyld cache))

CondaValueError: You have chosen a non-default solver backend (libmamba) but it was not recognized. Choose one of: classic

2

Hi, I have had the same exact error since yesterday after updating my miniconda environment. Please someone help as soon as possible.

3

I had same problem on M2 Macmini. I fixed this problem following procedure today.

  1. Search “libarchive.19.dylib” by Spotlight
  2. 3 files were catched in my M2 Macmini, so I copied the latest version among them.
  3. Pasted the latest version file mention above to the directory which was indicated in the command line.
    (In your case, “/Users/murraycantor/opt/anaconda3/lib/”)
    This procedure fixed the problem.
    I hope that my experience will give your solution.
4

One quick fix to this is to just run the command with the argument --solver classic. :cat_with_wry_smile:

I think it’s recommended to be running the libmamba solver, but for some reason struggles sometimes with an environment update? I had to run it with the above argument for updating my base environment with a conda update. In case anyone else struggles with the same issue I had, this is what I was trying to run:

conda --no-plugins update -n base -c conda-forge -c defaults anaconda-anon-usage conda-anaconda-telemetry conda-anaconda-tos

to which I had to slap on the --solver classic argument so my total argument was clearly,

conda --no-plugins update -n base --solver classic -c conda-forge -c defaults anaconda-anon-usage conda-anaconda-telemetry conda-anaconda-tos

This was happening for me because I was foolishly trying to update these three plugins without any other plugins. (One of the plugins that I needed was that libmamba solver.) This originally happened for me because I was trying to create a new environment after updating conda, and I guess these three plugins needed a little more specific updating… :kissing_cat: