How to change permalink from postname to category/postname

I come across to have some changes of the permanent link on my blog.

The requirement for the URL change are simple:
1. must have category slug in the URL
2. the old existing URL will be able to be redirected to new one.

so, how to do it?

Firstly, just download the plugin to take care of the redirection of old postname only urnl to new one.

you can download it from https://wordpress.org/plugins/postname-permalink-auto-redirect/

then just go to permalink setting, change it to custom with parameter as :

“/%category%/%postname%/”

to test, just hit the old url and check the “network” tab in inspect tool.
it should have been redirected successfully to new URL.

Goodluck.