[Python] ImportError when importing NumPy – missing libgfortran.5.dylib on macOS (VS Code,...

I’m working on macOS Sequoia 15.4, using VS Code and Jupyter Notebooks with Conda environments.

Everything worked fine until yesterday. Now, when I try to run any of my existing environments, importing NumPy or other scientific libraries results in the following ImportError related to libgfortran.5.dylib.

ImportError: dlopen(..._multiarray_umath.cpython-39-darwin.so):
Library not loaded: @rpath/libgfortran.5.dylib
Referenced from: /Users/.../miniconda3/envs/PARESIS/lib/libopenblasp-r0.3.21.dylib
Reason: tried: '/Users/.../libgfortran.5.dylib' (duplicate LC_RPATH '@loader_path'),
'/usr/local/lib/libgfortran.5.dylib' (no such file),
'/usr/lib/libgfortran.5.dylib' (no such file, not in dyld cache)


This ends with:

ImportError: Error importing numpy: you should not try to import numpy from
its source directory; please exit the numpy source tree, and relaunch
your python interpreter from there.


This happens only in older environments. If I create a new Conda environment, everything works fine.

I tried reinstalling NumPy using

conda install numpy --force-reinstall


, and also explicitly installing libgfortran=5 in the affected environment. I also updated Conda, restarted my system, and relaunched VS Code multiple times.

I expected NumPy to be reinstalled correctly and the missing library issue to be resolved, but the error persists. I was hoping to avoid recreating all my environments from scratch since I have a lot of dependencies already configured.

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