pdb throws an exception inside jupyter notebook

Hi,
I am a regular user of jupyter notebook. I used **import pdb** package to debug my codes. This was working perfectly fine till some days. But now PDB throws an exception. I don't understand what is the actual issue. Please, kindly help me to resolve this. Below i have pasted the error code and also the snapshot of a simple code in jupyter notebook.
Thank you,

--Return--
> (10)()->None
-> pdb.set_trace()
(Pdb) n
> /home/srinidhi/anaconda3/envs/pytorch/lib/python3.6/site-packages/IPython/core/interactiveshell.py(2964)run_code()
-> sys.excepthook = old_excepthook

Reproduce the reported minimal example using import pdb and pdb.set_trace() in a Jupyter Notebook with the shown Python 3.6 environment, then capture the complete traceback beyond the pasted output. Trace the interaction around IPython's run_code() and sys.excepthook; done means stepping with pdb no longer raises the reported exception.

Written by the indexing model from the issue text.