Hide error and warning in admin panel
Although it is not a good idea to hide the errors (you may want to solve it; by watching the error log, debugging etc.), there is a way you can do it.

You can do it at theme level in template_process_page() function, in your theme's template.php file. (It should be placed in your admin theme's template.php)
Code: Edited according to @Chapabu 's comments :)
Used path_is_admin() and current_path().

&lt;?php

function MYTHEME_process_page(&amp;$variables) {
  if (path_is_admin(current_path())) {
    unset($variables['messages']);
  }
}

?&gt;