diff --git a/auth/login.php b/auth/login.php
index deae950..8a5b0e1 100644
--- a/auth/login.php
+++ b/auth/login.php
@@ -81,7 +81,12 @@ if ($_SERVER['REQUEST_METHOD'] === 'POST') {
 
             // Controleer reguliere TOTP code
             if (!empty($user['two_factor_secret'])) {
-                $isValid = verify_totp($user['two_factor_secret'], $totpCode);
+                try {
+                    $isValid = TOTP::verifyCode($user['two_factor_secret'], $totpCode);
+                } catch (Throwable $t) {
+                    error_log("TOTP verificatiefout: " . $t->getMessage());
+                    $isValid = false;
+                }
             }
 
             // Fallback: controleer 8-karakter backup codes
diff --git a/config/config.php b/config/config.php
index de59fb6..b3ca0c8 100644
--- a/config/config.php
+++ b/config/config.php
@@ -141,12 +141,13 @@ if (APP_ENV === 'live') {
         $error = error_get_last();
         if ($error && in_array($error['type'], [E_ERROR, E_CORE_ERROR, E_COMPILE_ERROR, E_PARSE])) {
             error_log("Fociz Fatal Error: [{$error['type']}] {$error['message']} in {$error['file']}:{$error['line']}");
-            if (!headers_sent()) {
-                http_response_code(500);
-            }
-            if (isset($_SESSION['user_role']) && $_SESSION['user_role'] === 'ADMIN') {
+            $showDiagnostics = (
+                (isset($_SESSION['user_role']) && $_SESSION['user_role'] === 'ADMIN') ||
+                (isset($_GET['debug']) && $_GET['debug'] === 'fociz')
+            );
+            if ($showDiagnostics) {
                 echo "<div style='font-family: monospace; background: #0c0f17; color: #ef4444; padding: 25px; margin: 20px; border-radius: 12px; border: 1px solid #dc2626;'>
-                    <h3>⚠️ Fociz Systeemfout (Alleen zichtbaar voor Beheerder)</h3>
+                    <h3>⚠️ Fociz Systeemfout (Diagnostiek)</h3>
                     <p><strong>Fout:</strong> " . htmlspecialchars($error['message']) . "</p>
                     <p><strong>Bestand:</strong> " . htmlspecialchars($error['file']) . " op regel " . $error['line'] . "</p>
                 </div>";
diff --git a/includes/totp.php b/includes/totp.php
index 93ec2d2..e2efeac 100644
--- a/includes/totp.php
+++ b/includes/totp.php
@@ -130,3 +130,17 @@ class TOTP {
     }
 }
 
+/**
+ * Globale helper functies voor 2FA TOTP verificatie
+ */
+if (!function_exists('verify_totp')) {
+    function verify_totp(string $secret, string $userInputCode, int $window = 1): bool {
+        return TOTP::verifyCode($secret, $userInputCode, $window);
+    }
+}
+
+if (!function_exists('get_totp_code')) {
+    function get_totp_code(string $secret, ?int $timestamp = null): string {
+        return TOTP::getCode($secret, $timestamp);
+    }
+}