From 4256e4f5ca75b949a60e43fe2963a72c165848db Mon Sep 17 00:00:00 2001
From: albertlast <mathiaspapealbert@hotmail.com>
Date: Sat, 8 Aug 2026 17:51:17 +0200
Subject: [PATCH] Stops the forum offering to delete the language it falls back
 to
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

The language editor guards its delete button with

    if (Utils::$context['lang_id'] != 'english')

and the comment above it says English cannot be deleted. Language ids have not
looked like that since 2.1 — Lang.php maps 'english' to 'en_US' precisely because
it is the old name — so the comparison never matches anything and the button is
offered for every language, including the one the forum is running on. The check
that actually performs the deletion is spelled the same way, so it goes through.

Deleting en_US is worse than losing a translation: Lang::load() falls back to it
for any string the chosen language is missing, so a forum without it has no
backstop.

Guards on the forum's own default language and on en_US, decided once where
lang_id is settled and read by both the action and the template.

Signed-off-by: albertlast <mathiaspapealbert@hotmail.com>
---
 Sources/Actions/Admin/Languages.php         | 7 ++++++-
 Themes/default/ManageLanguages.template.php | 4 ++--
 2 files changed, 8 insertions(+), 3 deletions(-)

diff --git a/Sources/Actions/Admin/Languages.php b/Sources/Actions/Admin/Languages.php
index f482db58fa1..e0636dba07e 100644
--- a/Sources/Actions/Admin/Languages.php
+++ b/Sources/Actions/Admin/Languages.php
@@ -671,6 +671,11 @@ public function editEntries()
 
 		Utils::$context['lang_id'] = &$lang_id;
 
+		// Neither the forum's own default nor en_US can go. en_US is what
+		// Lang::load() falls back to for any string the chosen language is
+		// missing, so a forum without it has no backstop at all.
+		Utils::$context['can_delete_language'] = $lang_id !== 'en_US' && $lang_id !== Config::$language;
+
 		// Get all the theme data.
 		$themes = [
 			1 => [
@@ -792,7 +797,7 @@ function ($val1, $val2) {
 		}
 
 		// We no longer wish to speak this language.
-		if (!empty($_POST['delete_main']) && $lang_id != 'english') {
+		if (!empty($_POST['delete_main']) && Utils::$context['can_delete_language']) {
 			User::$me->checkSession();
 			SecurityToken::validate('admin-mlang');
 
diff --git a/Themes/default/ManageLanguages.template.php b/Themes/default/ManageLanguages.template.php
index 363b3c35c86..ee980005735 100644
--- a/Themes/default/ManageLanguages.template.php
+++ b/Themes/default/ManageLanguages.template.php
@@ -182,8 +182,8 @@ function template_modify_language_entries()
 				<input type="submit" name="save_main" value="', Lang::getTxt('save', file: 'General'), '"', !empty(Utils::$context['lang_file_not_writable_message']) ? ' disabled' : '', ' class="button">
 				<input type="reset" id="reset_main" value="', Lang::getTxt('reset', file: 'General'), '" class="button">';
 
-	// Allow deleting entries. English can't be deleted though.
-	if (Utils::$context['lang_id'] != 'english') {
+	// Allow deleting entries. The default language and en_US can't go.
+	if (Utils::$context['can_delete_language']) {
 		echo '
 				<input type="submit" name="delete_main" value="', Lang::getTxt('delete', file: 'General'), '"', !empty(Utils::$context['lang_file_not_writable_message']) ? ' disabled' : '', ' onclick="return confirm(\'', Lang::getTxt('languages_delete_confirm', file: 'ManageSettings'), '\');" class="button">';
 	}