Strange behaviour of is_user_logged_in() and get_current_user_id()

Question

I have an issue where is_user_logged_in() appears to alternate between being true and false.

Additionally, get_current_user_id() gives the correct user ID if is_user_logged_in() is true.

Here's my code:

.htaccess:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ - [L]

RewriteCond %{REQUEST_FILENAME} -s
RewriteRule ^wp-content/uploads/(.*)$ file-access.php?file=$1 [QSA,L]

RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>
# END WordPress

file-access.php:

require_once('wp-load.php');

if ( is_user_logged_in() ) {
    // User is logged in, proceed.
} else {
    // User is a guest, block.
}

I've verified the alternating status and user id using some error logging in the file-access.php conditionals.

Do I need to call something other than wp-load.php perhaps? Just seems strange to me that it alternates between true and false, rather than always being false...

Edit to add: I also had an issue where one of my files I was testing with wasn't uploaded as the https version which caused issues.

Answer 1

I've run your code and it works fine to me except for the inclusion in file-access.php:

require_once($_SERVER['DOCUMENT_ROOT'].'/wp-load.php'); enable debug to see if there are errors depending on other issues and not regarding these specific code lines.

But.. as per WP documentation: actions reference the earlier action hook where the authentication process is completed and cookies are set is init as suggested in @Mohsin comment so I suggest to use this code in file-access.php

/* you probably don't need a theme */ 
define( 'WP_USE_THEMES', false ); 

/* defining a constant here allows you to exit functions when not needed */
define('FROM_EXTERNAL_FILE',true);

/* unless you've renamed your wp-content folder this path will always point to wp-load.php even in subfolders installations */
require_once(explode("wp-content", __FILE__)[0] . "wp-load.php");

and move the check in your file functions.php which gets loaded with the whole WP environment by wp-load.php

function is_logged_function(){
  if ( !defined ('FROM_EXTERNAL_FILE') )
    return;
  if ( is_user_logged_in()){
    echo "logged";
    echo get_current_user_id();
  }
  else{
    echo "not logged";
  }
}
add_action('init', 'is_logged_function');

Answer 2

The file that would normally be called to kick off the Wordpress setup is wp-blog-header.php so maybe try swapping out wp-load.php for wp-blog-header.php in your code then re-test