What are common issues that can cause PHPBB2 login problems for users and administrators?

Common issues that can cause PHPBB2 login problems include incorrect login credentials, expired sessions, and cookie-related issues. To solve these problems, users and administrators should double-check their login information, clear browser cookies and cache, and ensure that session settings are configured correctly.

// Clear browser cookies and cache
setcookie("PHPSESSID", "", time()-3600, "/");
session_destroy();