显然这是因为包含该函数的文件/wp-includes/pluggable 在加载插件之后才会加载.

Apparently this is happening because the file /wp-includes/pluggable which contains the function doesn't get loaded until after the plugins are loaded.

确实如此.因此，将您正在做的任何事情包装在一个函数中，并将其挂接到 plugins_loaded 或 init 钩子上.(见 wp-settings.php 文件)

Indeed it is. So wrap whichever thing you're doing in a function, and hook it onto the plugins_loaded or init hook. (see the wp-settings.php file)

示例:

add_action('init','do_stuff');
function do_stuff(){
  $current_user = wp_get_current_user();
  // ...
}