[Error 404]When trying to add a new job position

When I trying to add a new job position and trying to preview it, it proceeds to error 404. Even save Draft and Publish, but it saves the draft but its empty inside. The buttons of save Draft, Preview, and Publish are directing to error 404 but I tried to copy address link the preview button, the link is there. I tried many things like deactivate and active the plugin again, deactivate some plugins, double checking the permalinks, and changing themes nothing works.