Vishal Barot

fixed it by following:

https://kainelabs.ticksy.com/article/13148/

well..
im not expert here,
make new category and check if newly created cats work or not.

i had same issue so i know how it feels,

give a try with this

if your current mod rewrite is

/%category%/%postname%/

than remove slash from the end

so it would be /%category%/%postname%

if your current mod rewrite is

/%category%/%postname%

than add slash at the end. so it would be

like

/%category%/%postname%/

it did worked for me.