1. Login to your Website Dashboard.
2. In the dashboard menu, hover you mouse over PressApps and click Knowledge Base, then click the General Tab.
3. Under the General tab, make sure that the Article Slug and Category Slug are unique.
4. When Creating a Knowledge Base main page, make sure that the slug is also unique from the Article Slug and Category Slug.
Flush permalinks on 404
1. On the Dashboard menu, go to Settings > Permalinks
2. Choose any of the following then click Save Changes at the bottom of the page.
3. Go back to the initial selection and click Save Changes again.