Running CiviCRM 4.7.31 on WordPress 4.9.5. When attempting to edit an existing membership type, I am receiving an error "Network Error: Unable to reach the server. Please refresh this page in your browser and try again." I refresh and get the same result. All other parts of CiviCRM are working fine. Any help is appreciated.
With such issues it is worth trying a 'right click' on the link to open the Edit screen as you may get to see an error message that you don't see with the pop up. If you find one, the repost in your Q