The error “We can’t display this page because your browser blocks cross-domain cookies” appears in Salesforce Lightning Experience when your browser refuses the cookies Salesforce needs to load a page from another Salesforce domain. Some versions add “but you can view this page in Salesforce Classic” or “Try again with a different supported browser.”
In this tutorial, I will explain why the error happens, the quick workaround, and the permanent fix with up-to-date steps for Chrome, Edge, Firefox, Brave and Safari. I will also cover what admins can check in the org, because in most orgs today the real fix is on the Salesforce side.