diff --git a/app/Debug.php b/app/Debug.php
index c6965f47f..3f582af09 100644
--- a/app/Debug.php
+++ b/app/Debug.php
@@ -240,14 +240,12 @@ class Debug {
             }
         }
 
-        if (DEBUG_WARNINGS) {
-            self::$Errors[] = [
-                str_replace(SERVER_ROOT . '/', '', $Error),
-                str_replace(SERVER_ROOT . '/', '', $File) . ":$Line",
-                $Call,
-                $Args
-            ];
-        }
+        self::$Errors[] = [
+            str_replace(SERVER_ROOT . '/', '', $Error),
+            str_replace(SERVER_ROOT . '/', '', $File) . ":$Line",
+            $Call,
+            $Args
+        ];
         return true;
     }
 
diff --git a/app/SessionCookie.php b/app/SessionCookie.php
index 0607b7e34..e44925b89 100644
--- a/app/SessionCookie.php
+++ b/app/SessionCookie.php
@@ -69,7 +69,7 @@ class SessionCookie {
             [
                 'expires'  => $expiryEpoch,
                 'path'     => '/',
-                'secure'   => !DEBUG_MODE,
+                'secure'   => SECURE_COOKIE,
                 'httponly' => true,
                 'samesite' => 'Lax',
             ]
@@ -83,7 +83,7 @@ class SessionCookie {
             [
                 'expires'  => time() - 86_400 * 90,
                 'path'     => '/',
-                'secure'   => !DEBUG_MODE,
+                'secure'   => SECURE_COOKIE,
                 'httponly' => true,
                 'samesite' => 'Lax',
             ]
diff --git a/app/User.php b/app/User.php
index 95944423b..aab584201 100644
--- a/app/User.php
+++ b/app/User.php
@@ -109,7 +109,7 @@ class User extends BaseAttrObject {
         setcookie('session', '', [
             'expires'  => time() - 60 * 60 * 24 * 90,
             'path'     => '/',
-            'secure'   => !DEBUG_MODE,
+            'secure'   => SECURE_COOKIE,
             'httponly' => true,
             'samesite' => 'Strict',
         ]);
diff --git a/app/Util/Twig.php b/app/Util/Twig.php
index 8c0032ffb..80c47bacd 100644
--- a/app/Util/Twig.php
+++ b/app/Util/Twig.php
@@ -24,7 +24,7 @@ class Twig {
         self::$userMan = $userMan;
         $twig = new \Twig\Environment(
             new \Twig\Loader\FilesystemLoader(__DIR__ . '/../../' . TEMPLATE_PATH), [
-                'debug' => DEBUG_MODE,
+                'debug' => DEBUG_TWIG,
                 'cache' => __DIR__ . '/../../cache/twig'
             ]);
 
diff --git a/classes/sphinxql.class.php b/classes/sphinxql.class.php
index 144172ab9..0ff21832c 100644
--- a/classes/sphinxql.class.php
+++ b/classes/sphinxql.class.php
@@ -92,7 +92,7 @@ class Sphinxql extends mysqli {
             86_400,
         );
         if ($halt === true) {
-            if (DEBUG_MODE || $Viewer->permitted('site_debug')) {
+            if ($Viewer->permitted('site_debug')) {
                 echo '<pre>' . display_str($error) . '</pre>';
                 die();
             } else {
diff --git a/gazelle.php b/gazelle.php
index ff7784c65..e9c9ee416 100644
--- a/gazelle.php
+++ b/gazelle.php
@@ -121,7 +121,7 @@ if ($Viewer) {
 }
 
 $Debug->mark('load page');
-if (DEBUG_MODE || $Viewer?->permitted('site_debug')) {
+if (DEBUG_TWIG) {
     $Twig->addExtension(new \Twig\Extension\DebugExtension());
 }
 
@@ -169,7 +169,7 @@ try {
     }
     $errorLog = $Debug->saveError($e);
     Error500::error(
-        DEBUG_MODE || $Viewer?->permitted('site_debug')
+        $Viewer?->permitted('site_debug')
             ? ($e->getMessage() . " ({$errorLog->link()})")
             : "That is not supposed to happen. Check to see whether someone has created a thread in the the Bugs forum, or create a new thread to explain what you were doing and reference the Error ID {$errorLog->id}."
     );
diff --git a/lib/config.php b/lib/config.php
index 64e603460..c95d37d19 100644
--- a/lib/config.php
+++ b/lib/config.php
@@ -479,11 +479,8 @@ defined('HTTP_PROXY') or define('HTTP_PROXY', false);
 // Block Opera Mini proxy?
 defined('BLOCK_OPERA_MINI') or define('BLOCK_OPERA_MINI', true);
 
-// Should PHP errors be shown in the output?
-defined('DEBUG_MODE') or define('DEBUG_MODE', false);
-
-// Can developer+ see PHP warnings in the site footer?
-defined('DEBUG_WARNINGS') or define('DEBUG_WARNINGS', true);
+// Is the debug() function available in Twig?
+defined('DEBUG_TWIG') or define('DEBUG_TWIG', false);
 
 // Do upload notifications need to be traced? (Results written to TMPDIR)
 defined('DEBUG_UPLOAD_NOTIFICATION') or define('DEBUG_UPLOAD_NOTIFICATION', false);
@@ -509,12 +506,6 @@ defined('LASTFM_API_KEY') or define('LASTFM_API_KEY', false);
 // Fake useragent (to override default cURL useragent string).
 defined('FAKE_USERAGENT') or define('FAKE_USERAGENT', 'Mozilla/5.0 (Windows NT 6.1) AppleWebKit/537.11 (KHTML, like Gecko) Chrome/23.0.1271.1 Safari/537.11');
 
-// How much upload buffer to members start out with? (3 GiB)
-defined('STARTING_UPLOAD') or define('STARTING_UPLOAD', 3 * 1024 * 1024 * 1024);
-
-// Can freeleech (FL) tokens be stacked?
-defined('STACKABLE_FREELEECH_TOKENS') or define('STACKABLE_FREELEECH_TOKENS', true);
-
 // How long does an activated token last before it is purged?
 defined('FREELEECH_TOKEN_EXPIRY_DAYS') or define('FREELEECH_TOKEN_EXPIRY_DAYS', 30);
 
@@ -542,6 +533,15 @@ defined('DELETE_USER_STATS_DAILY_DAY') or define('DELETE_USER_STATS_DAILY_DAY',
 // Retain this many months of daily snapshots.
 defined('DELETE_USER_STATS_MONTHLY_DAY') or define('DELETE_USER_STATS_MONTHLY_DAY', 120);
 
+// Is the secure attribute set on cookies?
+defined('SECURE_COOKIE') or define('SECURE_COOKIE', true);
+
+// Can freeleech (FL) tokens be stacked?
+defined('STACKABLE_FREELEECH_TOKENS') or define('STACKABLE_FREELEECH_TOKENS', true);
+
+// How much upload buffer to members start out with? (3 GiB)
+defined('STARTING_UPLOAD') or define('STARTING_UPLOAD', 3 * 1024 * 1024 * 1024);
+
 // How many invites do new users receive?
 defined('STARTING_INVITES') or define('STARTING_INVITES', 0);
 
diff --git a/misc/example.local.config.php b/misc/example.local.config.php
index 6ab3efb70..9bce21e68 100644
--- a/misc/example.local.config.php
+++ b/misc/example.local.config.php
@@ -9,11 +9,11 @@ define('DISABLE_TRACKER', true);
 define('DISABLE_IRC', true);
 
 define('DEBUG_EMAIL', true);
-define('DEBUG_MODE', true);
-define('DEBUG_WARNINGS', true);
+define('DEBUG_TWIG', true);
 define('DEBUG_UPLOAD_NOTIFICATION', true);
 
 define('OPEN_REGISTRATION', true);
+define('SECURE_COOKIE', false);
 
 define('MEMCACHE_HOST_LIST', [['host' => 'memcached', 'port' => 11211, 'buckets' => 1]]);
 
diff --git a/misc/phpstan.neon b/misc/phpstan.neon
index a38e8e35d..9f03ba61d 100644
--- a/misc/phpstan.neon
+++ b/misc/phpstan.neon
@@ -76,10 +76,9 @@ parameters:
         - DEBUG
         - DEBUG_CONTEST_PAYOUT
         - DEBUG_EMAIL
-        - DEBUG_MODE
         - DEBUG_TRACKER_TOKEN_EXPIRE
+        - DEBUG_TWIG
         - DEBUG_UPLOAD_NOTIFICATION
-        - DEBUG_WARNINGS
         - FEATURE_EMAIL_REENABLE
         - GEOIP_SERVER
         - HTTP_PROXY
@@ -103,6 +102,7 @@ parameters:
         - RECOVERY_DB
         - REFERRAL_SEND_EMAIL
         - REQUEST_TAX
+        - SECURE_COOKIE
         - SHOW_PUBLIC_INDEX
         - STACKABLE_FREELEECH_TOKENS
         - USER_LIMIT
diff --git a/misc/rector.php b/misc/rector.php
index 69d185222..bb3364271 100644
--- a/misc/rector.php
+++ b/misc/rector.php
@@ -10,8 +10,7 @@ use Rector\Php83\Rector\ClassConst\AddTypeToConstRector;
 use Rector\Php83\Rector\ClassMethod\AddOverrideAttributeToOverriddenMethodsRector;
 
 // phpcs:disable PSR1.Files.SideEffects.FoundWithSymbols
-define('DEBUG_MODE', true);
-define('DEBUG_WARNINGS', true);
+define('DEBUG_TWIG', true);
 define('DISABLE_IRC', false);
 define('FEATURE_EMAIL_REENABLE', true);
 define('GEOIP_SERVER', true);
@@ -24,6 +23,7 @@ define('REAPER_TASK_NOTIFY', true);
 define('REAPER_TASK_REMOVE_UNSEEDED', true);
 define('REAPER_TASK_REMOVE_NEVER_SEEDED', true);
 define('RECOVERY_AUTOVALIDATE', true);
+define('SECURE_COOKIE', false);
 
 return RectorConfig::configure()
     ->withPaths([
diff --git a/sections/login/disabled.php b/sections/login/disabled.php
index 06d3f1b71..cf1185d92 100644
--- a/sections/login/disabled.php
+++ b/sections/login/disabled.php
@@ -14,7 +14,7 @@ if (isset($_POST['username'])) {
             setcookie('username', '', [
                 'expires'  => time() + 60 * 60,
                 'path'     => '/',
-                'secure'   => !DEBUG_MODE,
+                'secure'   => SECURE_COOKIE,
                 'httponly' => true,
                 'samesite' => 'Strict',
             ]);
diff --git a/sections/login/login.php b/sections/login/login.php
index 5dc130655..c3184596c 100644
--- a/sections/login/login.php
+++ b/sections/login/login.php
@@ -29,7 +29,7 @@ if (!empty($_POST['username']) && !empty($_POST['password'])) {
                 setcookie('username', urlencode($user->username()), [
                     'expires'  => time() + 60 * 60,
                     'path'     => '/',
-                    'secure'   => !DEBUG_MODE,
+                    'secure'   => SECURE_COOKIE,
                     'httponly' => true,
                     'samesite' => 'Strict',
                 ]);
diff --git a/templates/index/private-footer.twig b/templates/index/private-footer.twig
index 3f8229326..fc846d2bc 100644
--- a/templates/index/private-footer.twig
+++ b/templates/index/private-footer.twig
@@ -1,6 +1,6 @@
 </div>
 <div id="footer">
-{% if constant('DEBUG_MODE') or viewer.permitted('site_debug') %}
+{% if viewer.permitted('site_debug') %}
     <div id="site_debug">
 {%  include 'debug/performance.twig' with {'list': debug.perfInfo} only %}
 {%  include 'debug/flag.twig' with {'list': debug.markList} only %}
diff --git a/templates/index/private-header.twig b/templates/index/private-header.twig
index 04452741f..8c1b06eab 100644
--- a/templates/index/private-header.twig
+++ b/templates/index/private-header.twig
@@ -57,7 +57,7 @@
 <script type="text/javascript" src="{{ constant('STATIC_SERVER') }}/vendor/noty/noty.layout.bottomRight.js?v={{ mtime('vendor/noty/noty.layout.bottomRight.js') }}"></script>
 <script type="text/javascript" src="{{ constant('STATIC_SERVER') }}/vendor/noty/noty.theme.default.js?v={{ mtime('vendor/noty/noty.theme.default.js') }}"></script>
 {% endif %}
-{% if constant('DEBUG_MODE') or viewer.permitted('site_debug') %}
+{% if viewer.permitted('site_debug') %}
 <script type="text/javascript" src="{{ constant('STATIC_SERVER') }}/vendor/jquery-migrate.js?v={{ mtime('vendor/jquery-migrate.js') }}"></script>
 <script type="text/javascript" src="{{ constant('STATIC_SERVER') }}/functions/debug.js?v={{ mtime('functions/debug.js') }}"></script>
 {% endif %}