This error (ERR_TOO_MANY_REDIRECTS) means the browser is being sent round in a loop, for example from http to https and back again.
1. Clear cookies and cache
Clear cookies for the site, or try a private/incognito window, to rule out an old saved redirect.
2. Check .htaccess
In File Manager, rename .htaccess to .htaccess.disabled and reload the site. If the loop stops, a rule in that file is the cause. Look for HTTPS or www redirects that conflict with each other.
3. Check for duplicate HTTPS redirects
You only need one. If Force HTTPS Redirect is on in cPanel, remove HTTPS redirect rules from .htaccess and from plugins such as Really Simple SSL.
4. WordPress address
In WordPress (Settings › General), both addresses should match exactly, including https and whether you use www.
5. Cloudflare
If you use Cloudflare, set SSL/TLS encryption mode to Full or Full (strict). The Flexible setting causes loops when the server also redirects to HTTPS.
Rename .htaccess back once you've found and fixed the rule.
