IPython 3.5 returns "bad interpreter: No such file or directory"

Question

I am getting random error while trying to use IPython. I now suddenly cannot use iPython3 with no explanation, I don't remember installing anything heavy besides Ethereum client and I didn't download the hashes or anything. Suddenly I get:

cchilders:~ 
$ ipython3
-bash: /usr/local/bin/ipython3: /usr/local/opt/python3/bin/python3.5: bad interpreter: No such file or directory

neither IPython or IPython3 was working. After uninstalling and reinstalling Python and Python3, I can now use IPython. But the same error from before happens if I try iPython3.

This is one of the more absurd errors I've seen because I've reinstalled IPython, Python itself, and Python3 with no change.

Answer 1

As described here, the problem is that ipython3 is trying to use the python3.5 kernel in /usr/local/opt/python3/bin/python3.5. You can view which kernel ipython3 is trying to use by running:

jupyter kernelspec list

and then viewing the kernel.json file which is in the python3 kernel's path (in my case, the path to kernel.json is: /usr/local/share/jupyter/kernels/python3/kernel.json).

To solve this, I had to reinstall all of the following jupyter packages:

$ pip3 uninstall jupyter jupyter-client jupyter-console jupyter-core
$ pip3 install jupyter jupyter-client jupyter-console jupyter-core

Answer 2

If you are not a Jupyter user, this can be solved by reinstalling ipython

pip uninstall ipython
pip install ipython

I found that I needed sudo to uninstall it due to some additional errors. You may not need it.