Upgraded to Laravel 5.6

app/Http/Middleware/CheckForMaintenanceMode.php

@@ -0,0 +1,17 @@
+<?php
+
+namespace BookStack\Http\Middleware;
+
+use Illuminate\Foundation\Http\Middleware\CheckForMaintenanceMode as Middleware;
+
+class CheckForMaintenanceMode extends Middleware
+{
+    /**
+     * The URIs that should be reachable while maintenance mode is enabled.
+     *
+     * @var array
+     */
+    protected $except = [
+        //
+    ];
+}

app/Http/Middleware/TrustProxies.php

@@ -16,17 +16,11 @@ class TrustProxies extends Middleware
     protected $proxies;
 
     /**
-     * The current proxy header mappings.
+     * The headers that should be used to detect proxies.
      *
-     * @var array
+     * @var int
      */
-    protected $headers = [
-        Request::HEADER_FORWARDED => 'FORWARDED',
-        Request::HEADER_X_FORWARDED_FOR => 'X_FORWARDED_FOR',
-        Request::HEADER_X_FORWARDED_HOST => 'X_FORWARDED_HOST',
-        Request::HEADER_X_FORWARDED_PORT => 'X_FORWARDED_PORT',
-        Request::HEADER_X_FORWARDED_PROTO => 'X_FORWARDED_PROTO',
-    ];
+    protected $headers = Request::HEADER_X_FORWARDED_ALL;
 
     /**
      * Handle the request, Set the correct user-configured proxy information.