XGBoostError and libomp

Just in case you find yourself in my situation. Trying to run a Python/XGBoost script on a Mac, and keep getting this

raise XGBoostError(
xgboost.core.XGBoostError:
XGBoost Library (libxgboost.dylib) could not be loaded.
Likely causes:
  * OpenMP runtime is not installed
    - vcomp140.dll or libgomp-1.dll for Windows
    - libomp.dylib for Mac OSX
    - libgomp.so for Linux and other UNIX-like OSes
    Mac OSX users: Run `brew install libomp` to install OpenMP runtime.

  * You are running 32-bit Python on a 64-bit OS

% brew install libomp
==> Downloading https://formulae.brew.sh/api/formula.jws.json
==> Downloading https://formulae.brew.sh/api/cask.jws.json
Warning: libomp 20.1.3 is already installed and up-to-date.
To reinstall 20.1.3, run:
  brew reinstall libomp

% brew reinstall libomp
==> Downloading https://ghcr.io/v2/homebrew/core/libomp/manifests/20.1.3
Already downloaded: /Users/john/Library/Caches/Homebrew/downloads/6fb106d95811ad1827b4ad653f3b94cb6dd44ceb8a4a4fb00355021f4d682a56--libomp-20.1.3.bottle_manifest.json
==> Fetching libomp
==> Downloading https://ghcr.io/v2/homebrew/core/libomp/blobs/sha256:70ca0ae9df9f32ef88357ad35efa5b20ee8d91419e385fb0722e52605bceb03b
Already downloaded: /Users/john/Library/Caches/Homebrew/downloads/9778a89c5d8464108701848888f35c0f20e4f3aae0ad620c0c79cefab06719d9--libomp--20.1.3.arm64_sequoia.bottle.tar.gz
==> Reinstalling libomp
==> Pouring libomp--20.1.3.arm64_sequoia.bottle.tar.gz
==> Caveats
libomp is keg-only, which means it was not symlinked into /Volumes/ExternalSSD/opt/homebrew,
because it can override GCC headers and result in broken builds.

For compilers to find libomp you may need to set:
  export LDFLAGS="-L/Volumes/ExternalSSD/opt/homebrew/opt/libomp/lib"
  export CPPFLAGS="-I/Volumes/ExternalSSD/opt/homebrew/opt/libomp/include"
==> Summary
🍺  /Volumes/ExternalSSD/opt/homebrew/Cellar/libomp/20.1.3: 9 files, 1.7MB
==> Running `brew cleanup libomp`...
Disable this behaviour by setting HOMEBREW_NO_INSTALL_CLEANUP.
Hide these hints with HOMEBREW_NO_ENV_HINTS (see `man brew`).

Any chance you have HOMEBREW configured for a non-default location?

% env | grep HOMEBREW
HOMEBREW_CASK_OPTS=--appdir=/Volumes/ExternalSSD/opt/homebrew/Applications
HOMEBREW_TEMP=/Volumes/ExternalSSD/opt/homebrew/tmp

Try this (update the paths of course)

% find /Volumes/ExternalSSD/opt/homebrew -name libomp.dylib 2>/dev/null
/Volumes/ExternalSSD/opt/homebrew/Cellar/libomp/20.1.3/lib/libomp.dylib

% sudo mkdir -p /opt/homebrew/opt/libomp/lib
Password:

% sudo ln -s /Volumes/ExternalSSD/opt/homebrew/Cellar/libomp/20.1.3/lib/libomp.dylib /opt/homebrew/opt/libomp/lib/libomp.dylib