title: ACF error on wp-login.php
body: <p>I am using Wordpress 4.3.1 and using ACF (Advanced custom fields) 5.3.0. I have following errors in "wp-login.php".</p>
  
  <p>Warning: call_user_func() expects parameter 1 to be a valid callback, function 's.t.r.r.e.v' not found or invalid function name in /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php on line 319</p>
  
  <p>Warning: call_user_func() expects parameter 1 to be a valid callback, function 's.t.r.r.e.v' not found or invalid function name in /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php on line 320</p>
  
  <p>Warning: call_user_func() expects parameter 1 to be a valid callback, function 's.t.r.r.e.v' not found or invalid function name in /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php on line 325</p>
  
  <p>Warning: call_user_func() expects parameter 1 to be a valid callback, no array or string given in /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php on line 326</p>
  
  <p>Warning: call_user_func() expects parameter 1 to be a valid callback, function 's.t.r.r.e.v' not found or invalid function name in /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php on line 327</p>
  
  <p>Warning: Cannot modify header information - headers already sent by (output started at /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php:319) in /www/htdocs/w00e3b8f/wp-content/plugins/advanced-custom-fields-pro/core/field.php on line 328</p>
  
  <p>Do you have any idea how to resolve these errors ?</p>