If you host a WordPress membership site you may well be using the popular Ultimate Member plugin and chances are if you’ve updated to Version 2 you may be wondering what’s causing the ERR_TOO_MANY_REDIRECTS warning. There doesn’t seem to be a one fit suits all solution but it’s worth checking Home isn’t set as the Logout page as that can cause redirects. You can check your settings by going to Dashboard -> Ultimate Member -> Settings -> General. If you find yourself getting a 404 error try logging in via your browser’s Incognito mode.
If you’re having this problem check out this plugin WP-Clear-File-Cache which makes it easy to clear the new file cache on WordPress 4.9. Saves a lot of head scratching.