404 Error with the Portfolio Pagination

If you have a 404 error when trying to go to the next page in your portfolio, this is a slug conflict between your page and your portfolio items. To fix this problem, rename the slug of your page or that of your portfolio items, to do this, go to the Portfolio > General section of the customizer, edit the Portfolio Item Slug field, then, go to your WordPress dashboard, click Settings > Permalinks, simply click on the Save Changes button and your problem will be solved!