How do I re-save all users?
I don't know how comfortable you are with code. I would suggest writing an update hook in a custom module. Something like:

MYMODULE_update_8100(&amp;$sandbox) {
  // On the initial run, set up the update.
  if (empty($sandbox)) {
    // Get all user ids.
    $sandbox['items'] = \Drupal::entityQuery('user')
      -&gt;accessCheck(FALSE)
      -&gt;execute();
    $sandbox['max'] = count($sandbox['items']);

    if (!$sandbox['max']) {
      // Prevent division by zero if there are no users.
      $sandbox['#finished'] = 1;
      return;
    }
  }

  $iteration = 0;
  while ($iteration &lt; 25 &amp;&amp; $sandbox['items']) {
    $iteration ++;

    // Resave each user.
    \Drupal::entityTypeManager()
      -&gt;getStorage('user')
      -&gt;load(end($sandbox['items']))
      -&gt;save();

    // Remove the end of the items list when the item has finished 
    // processing.
    array_pop($sandbox['items']);
  }

  // Update the completion status as a number between 0 and 1.
  $sandbox['#finished'] = ($sandbox['max'] - count($sandbox['items']) / $sandbox['max'];
}


See hook_update_N for more information.