[wp-trac] [WordPress Trac] #64249: Automatic translation (JIT) loading doesn't work for network-activated plugins in multisite

[WordPress Trac]

#64249: Automatic translation (JIT) loading doesn't work for network-activated
plugins in multisite
--------------------------+-----------------------------
 Reporter:  pelentak      |      Owner:  (none)
     Type:  defect (bug)  |     Status:  new
 Priority:  normal        |  Milestone:  Awaiting Review
Component:  I18N          |    Version:  trunk
 Severity:  normal        |   Keywords:  needs-patch
  Focuses:  multisite     |
--------------------------+-----------------------------
 == Description

 The automatic just-in-time (JIT) translation loading introduced in [59461]
 for WordPress 6.7+ only registers text domains for site-level active
 plugins, but completely skips network-activated plugins in multisite
 environments.

 This causes PHP translations (via `__()`, `_e()`, etc.) to fail for
 network-activated plugins, even when the plugin has correct Text Domain
 and Domain Path headers and translation files are present. Interestingly,
 JavaScript translations (`.json` files) continue to work correctly.


 == Possible Root Cause

 In wp-settings.php, the automatic translation registration code processes
 plugins from `wp_get_active_and_valid_plugins()` but does not process
 plugins from `wp_get_active_network_plugins()`.

 The relevant code added in [59461] around line 380-390 of wp-settings.php:

 {{{#!php
 <?php
 // Register plugin translations for active plugins
 foreach ( wp_get_active_and_valid_plugins() as $plugin ) {
     $plugin_data = get_plugin_data( $plugin, false, false );

     if ( ! empty( $plugin_data['TextDomain'] ) && ! empty(
 $plugin_data['DomainPath'] ) ) {
         // Translation registration happens here
     }
 }
 }}}


 However, there is no equivalent loop for network-activated plugins loaded
 earlier via `wp_get_active_network_plugins()`.



 == Steps to Reproduce

 Set up a WordPress Multisite installation (any configuration: subdirectory
 or subdomain)
 Create or install a plugin with:

 Proper plugin headers including `Text Domain: my-plugin` and `Domain Path:
 /languages`
 Translation files in the plugin's `/languages` directory (e.g., `my-
 plugin-de_DE.mo`)
 PHP code using translation functions like `__('Text', 'my-plugin')`


 Network Activate the plugin
 Set the site language to match the translation file (e.g., German de_DE)
 View the plugin's output on the front-end or admin


 == Expected Behavior

 The plugin's translations should load automatically without requiring
 `load_plugin_textdomain()`, just as they do for site-level activated
 plugins. The plugin should display translated text in German.


 == Actual Behavior

 The plugin displays English text (the original untranslated strings)
 because the text domain was never registered during the WordPress
 bootstrap process. Network-activated plugins must explicitly call
 `load_plugin_textdomain()` as a workaround.

-- 
Ticket URL: <https://core.trac.wordpress.org/ticket/64249>
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