Browser
ERR_TOO_MANY_REDIRECTS The page kept redirecting
What it means
The browser was sent from one URL to another, then another, and gave up when the chain did not stop. Something in the site's redirects, or in a cookie-based decision, is looping.
Where you usually see it
Sites with a bad HTTPS redirect, a language or login loop, or a mix of rules in a content delivery network and on the origin. It can also appear if a stale cookie keeps sending you around.
What to try first
Try a private window, which starts without your ordinary cookies. If the page loads there, clear cookies for that site only in your usual browser and try again. If it fails everywhere, the site's redirect rules need a fix by the operator.
When to stop
Clearing all cookies on the whole browser is heavier than you need for one looping site. Do not keep following a loop in the address bar hoping it will settle.