See https://github.com/sagemath/sage/issues/40605#issuecomment-3368103016 and the referenced issue in the jupyter repo for more details.
On Wednesday, January 7, 2026 at 1:03:21 AM UTC+1 Nils Bruin wrote: > OK, I made some progress on this. > > Even to get the kernel working properly for "sage --notebook jupyterlab" I > needed to manually run > > from sage.repl.ipython_kernel.install import Sage > KernelSpec SageKernelSpec.update() > > I would have expected this to be done for me as it was before. > (the info is here: > https://doc.sagemath.org/html/en/reference/repl/sage/repl/ipython_kernel/install.html > > ) > > This ends up installing the kernel in `~/.local/share/jupyter/kernels`. > That directory also gets used by the system `jupyter lab` but the kernel as > installed doesn't run properly because it assume sage's venv, which isn't > active when you just run `jupyter lab`. > > I ended up editing the kernel.json to read: > > {"argv": ["sage", "--python", "-m", "sage.repl.ipython_kernel", "-f", > "{connection_file}"], "display_name": "SageMath", "language": "sage"} > > so that the kernel gets started through python as sage starts it (assuming > "sage" is in the path). > > In particular, the instructions in > > > https://doc.sagemath.org/html/en/installation/launching.html#setting-up-sagemath-as-a-jupyter-kernel-in-an-existing-jupyter-notebook-or-jupyterlab-installation > > don't work properly, because the kernelspec file that is installed assumes > the venv is already activated, which is not the case when jupyter is run > normally. In fact it shouldn't be: it's entirely possible to have kernels > installed that depend on pip --user installs. Those are generally screened > out in a venv. So the right thing to do is to run the jupyter server in > whatever environment is usual and only activate the venv for the sage > kernel. > > Something did break recently in the updating of these kernels. I suspect > when things got switched over to meson (which still hangs for 4 minutes > before proceeding with an install!) > On Tuesday, 6 January 2026 at 12:48:41 UTC-8 Nils Bruin wrote: > >> It seems that 10.9.beta1 has broken the jupyter kernel functionality in >> sage. >> >> The kernel used to live in >> >> <SAGE_ROOT>/venv/share/jupyter/kernels/sagemath >> >> In fact, the files are still there but they don't point to the right >> kernel anymore. It does seem to be the kernelspec that gets picked up, both >> by `jupyter lab` and by `sage --notebook jupyterlab`, but the kernel fails >> to initialize (probably because it's pointing to files that don't exist). >> >> Where is the kernel living nowadays? >> > -- You received this message because you are subscribed to the Google Groups "sage-devel" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion visit https://groups.google.com/d/msgid/sage-devel/267922b4-a736-4609-858f-72bd2dca11e6n%40googlegroups.com.
