Hi, this article is related to bash tab completion is not working for specfic user on ubuntu/linux systems.

are you also facing the same, then this article is for you

The reason may be is that you create the new user for the system with /bin/sh and that user pointing to /bin/sh instead of /bin/bash after login.So you can change user's login shell with the 'chsh' command

sudo chsh -s /bin/bash <username>

And if you still getting the issue with root user also then you should do simpily

sudo apt install bash-completion

OR

sudo apt install --reinstall bash-completion

it will solve the your issue, hopes this helps