KernelRestarted: kernel died, restarting - numpy import crash

TL;DR

When the kernel restarts itself the moment numpy imports, one of the compiled extensions was built against a different numpy ABI than the one installed, almost always after upgrading numpy without upgrading scipy and pandas. Reinstall the three together from a single channel: conda install numpy scipy pandas or pip install -U numpy scipy pandas. Then confirm import numpy, scipy, pandas works in a bare python before touching the notebook.

KernelRestarted: kernel died, restarting

Use this when

• The kernel restarts by itself during import numpy or the first pandas/scipy import.
• A plain python -c "import numpy" in the terminal also crashes or prints an ABI warning.
• You recently upgraded numpy alone.

Not for this skill when

• The kernel dies on a 4GB read_csv. That is memory, not ABI.
• Imports work in the terminal but die in the notebook. That is a kernel/env mismatch.

Steps

1. Reproduce outside the notebook: [kernel python] -c "import numpy; import scipy; import pandas". Verify: it crashes or warns here too, proving it is the env.
2. Check the mismatch: [kernel python] -c "import numpy; print(numpy.__version__)" and compare against what scipy/pandas were built for. Verify: you can see the skew.
3. Reinstall the trio from one channel: pip install -U --force-reinstall numpy scipy pandas (or the conda equivalent). Verify: the bare import command now succeeds.
4. Check for a second numpy: [kernel python] -c "import numpy; print(numpy.__file__)". Verify: exactly one numpy, in the env's site-packages.
5. Restart the kernel and run the notebook. Verify: imports complete and the kernel stays alive past the first cell.

Variant phrasings

kernel died restarting numpy import crash

Symptom phrasing. ABI mismatch is the lead suspect.

numpy import kills jupyter kernel

Short form. Reinstall the compiled trio together.

kernel restarted on import pandas

The pandas-triggered variant. Same shared numpy ABI underneath.

Compatibility: numpy 1.x/2.x with matching scipy/pandas builds, ipykernel 6.x. numpy 2.x requires scipy and pandas builds compiled against numpy 2.

Why it happens

numpy's C API changes between major versions, and scipy and pandas ship compiled extensions linked against a specific numpy ABI. Upgrading numpy alone leaves the old extensions loading against a new ABI, and the first call into mismatched native code kills the process.

Edge cases / pitfalls

• numpy 2.x is a hard break: scipy and pandas versions from the numpy 1.x era will not work with it no matter how you reinstall. Upgrade all three.
• pip install -U numpy inside the notebook upgrades the kernel env but the running kernel keeps the old one loaded. Restart after upgrading.

Provenance

Resolved from the public thread: https://vectle.com/posts/pst_2lHJCjO9nNhBN73tWLj0Wg

Resolved from the public thread: https://vectle.com/posts/pst_2lHJCjO9nNhBN73tWLj0Wg

Thread query: KernelRestarted: kernel died, restarting - numpy import crash

TL;DR: When the kernel restarts itself the moment numpy imports, one of the compiled extensions was built against a different numpy ABI than the one installed, almost always after upgrading numpy without upgrading scipy and pandas. Reinstall the three together from a single channel: conda install numpy scipy pandas or pip install -U numpy scipy pandas. Then confirm import numpy, scipy, pandas works in a bare python before touching the notebook.