[wp-trac] [WordPress Trac] #64087: Deprecated urlencode() passing null warning during load-styles.php because get_stylesheet_directory() returns empty

[WordPress Trac]

#64087: Deprecated urlencode() passing null warning during load-styles.php because
get_stylesheet_directory() returns empty
-------------------------------------------------+-------------------------
 Reporter:  jerclarke                            |      Owner:  (none)
     Type:  defect (bug)                         |     Status:  new
 Priority:  normal                               |  Milestone:  Awaiting
                                                 |  Review
Component:  Script Loader                        |    Version:  6.8.3
 Severity:  minor                                |   Keywords:  2nd-opinion
  Focuses:  administration, performance, php-    |
  compatibility                                  |
-------------------------------------------------+-------------------------
 I'm getting the following in my PHP error logs (nginx+php 8.3):


 {{{
 [08-Oct-2025 19:06:54] PHP deprecated: "urlencode(): Passing null to
 parameter #1 ($string) of type string is deprecated" file: [...]/wp-
 includes/script-loader.php:1680 url: example.com/wp-admin/load-
 styles.php?c=0&dir=ltr&load%5Bchunk_0%5D=dashicons,admin-bar,buttons
 ,media-views,common,forms,admin-menu,dashboard,list-
 tables,edit,revisions,media,themes,about,nav-menu&load%5Bchunk_1%5D=s,wp-
 pointer,widgets,site-icon,l10n,wp-auth-check,wp-color-picker&ver=6.8.3
 [08-Oct-2025 19:06:54] PHP deprecated: "file_exists(): Passing null to
 parameter #1 ($filename) of type string is deprecated" file: [...]/wp-
 includes/global-styles-and-settings.php:429 url: example.com/wp-admin
 /load-styles.php?c=0&dir=ltr&load%5Bchunk_0%5D=dashicons,admin-bar,buttons
 ,media-views,common,forms,admin-menu,dashboard,list-
 tables,edit,revisions,media,themes,about,nav-menu&load%5Bchunk_1%5D=s,wp-
 pointer,widgets,site-icon,l10n,wp-auth-check,wp-color-picker&ver=6.8.3
 }}}

 They always come together and seem to be related, though this ticket is
 specifically about the first one because I've narrowed it down to
 something specific.

 First, the deprecation warning is clearly a new thing in PHP 8.x, so it
 makes sense this was never noticed before.

 As you can see in the error, it happens when loading `load-styles.php`.
 The line with the error is in `wp_theme_has_theme_json()`:

 {{{
         $theme_has_support[ $stylesheet ] = file_exists( $path );
 }}}

 Makes sense that if `$path` is empty, deprecation warning will show.

 Using Xdebug I determined that the reason it's empty is that it uses
 `get_stylesheet()`, `get_stylesheet_directory()`, and
 `get_template_directory()`, all of which return `null` in the context of
 `load-styles.php`.

 If I debug `wp_theme_has_theme_json()` on a wp-admin screen, those
 functions return strings and a `$path` is created, but in `load-
 styles.php` they come up empty and the deprecation warning is the result.

 I tested this with a totally vanilla copy of WP using twenty-twentyfive
 and had the same results.

 Note that the errors don't show on my local Valet+nginx installation, they
 only arrive in the logs of my live server for some reason. That said,
 Xdebug confirms that the problem exists locally as well, albeit silently.

 FWIW it doesn't seem like this actually breaks anything, I only noticed it
 because it fills up my server's error logs (effectively notifying me when
 a user has logged in with a cold CSS cache). It seems plausible to me that
 the "failure" of `get_stylesheet()` etc. is a long-time accepted state of
 affairs, since it doesn't hurt anything as the theme doesn't affect these
 scripts.

 Still, I think it should be fixed one way or another, whether making those
 stylesheet functions work in `load-styles.php`, or just fixing
 `wp_theme_has_theme_json()` to not call `file_exists()` if `$path` is
 empty.

 Thanks to anyone who can look into this and confirm or deny my conclusion
 that it is indeed an issue that affects all WP installs.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/64087>
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