GO THERE

app/Modules/Tutorials/Controllers/TutorialController.php

@@ -606,7 +606,7 @@ class TutorialController extends Controller
                 @unlink($tmpOutput);
 
                 $response = new Response();
-                return $response->html($pdfContent, 200, [
+                return $response->html($pdfContent, 200)->withHeaders([
                     'Content-Type' => 'application/pdf',
                     'Content-Disposition' => 'attachment; filename="Book-of-the-ERP.pdf"',
                     'Content-Length' => (string) strlen($pdfContent),
@@ -616,7 +616,7 @@ class TutorialController extends Controller
         }
 
         $response = new Response();
-        return $response->html($html, 200, [
+        return $response->html($html, 200)->withHeaders([
             'Content-Type' => 'text/html; charset=utf-8',
             'Content-Disposition' => 'attachment; filename="Book-of-the-ERP.html"',
         ]);

app/Shared/Services/PdfExportService.php

@@ -23,8 +23,7 @@ final class PdfExportService
         $html = ob_get_clean();
 
         $response = new Response();
-        return $response->html($html, 200, [
-            'Content-Type' => 'text/html; charset=utf-8',
+        return $response->html($html, 200)->withHeaders([
             'Content-Disposition' => 'attachment; filename="' . $filename . '"',
         ]);
     }
@@ -61,7 +60,7 @@ final class PdfExportService
                 @unlink($tmpOutput);
 
                 $response = new Response();
-                return $response->html($pdfContent, 200, [
+                return $response->html($pdfContent, 200)->withHeaders([
                     'Content-Type' => 'application/pdf',
                     'Content-Disposition' => 'attachment; filename="' . $filename . '"',
                     'Content-Length' => (string) strlen($pdfContent),
@@ -71,8 +70,7 @@ final class PdfExportService
         }
 
         $response = new Response();
-        return $response->html($html, 200, [
-            'Content-Type' => 'text/html; charset=utf-8',
+        return $response->html($html, 200)->withHeaders([
             'Content-Disposition' => 'attachment; filename="' . str_replace('.pdf', '.html', $filename) . '"',
         ]);
     }