Solving Drupal 6 Login Problem in PHP

If users are unable to log into an existing Drupal 6 site after upgrading PHP, then the following steps may help resolve the issue.

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1. In the Drupal folder, open the file that handles the user sessions.

includes/session.inc

2. Find the sess_regenerate() function and add the lines marked "After PHP upgrade" as follows.

// BEGIN CODE

/**
 * Called when an anonymous user becomes authenticated or vice-versa.
 */
function sess_regenerate() {
  global $user; //After PHP upgrade
  $old_session_id = session_id();

  // ...
  if (isset($_COOKIE[session_name()])) {
    setcookie(session_name(), '', time() - 42000, '/');
  }

  $temp = $user; //After PHP upgrade
  session_regenerate_id();
  $user = $temp; //After PHP upgrade

  db_query("UPDATE {sessions} SET sid = '%s' WHERE sid = '%s'", session_id(), $old_session_id);
}

// END CODE

3. Save the file, reload the page and log in.

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