Thread: change default permaink to "/%category%/%postname%-%post_id%/"

change default permaink to "/%category%/%postname%-%post_id%/"

Hi,
I have a well discussed issue on permalink, but still I can't find a solution for my problem.
I just bought classpiress theme and while configuring it, I wanted to update permalink from "?p=123" to "/%category%/%postname%-%post_id%/". But when I updated the config, I just keep having not found blank page. I'm new in this field, please can you help me fix this ?
I've already tried editing htacess file and so on ...