Try 1 to fix the problem after Slim Framework 4 upgrade when running grocy in a subdirectory

app.php

@@ -4,6 +4,7 @@ use Psr\Http\Message\ServerRequestInterface as Request;
 use Psr\Http\Message\ResponseInterface as Response;
 use Psr\Container\ContainerInterface as Container;
 use Slim\Factory\AppFactory;
+use Selective\BasePath\BasePathMiddleware;
 
 use Grocy\Helpers\UrlManager;
 use Grocy\Controllers\LoginController;
@@ -70,6 +71,7 @@ require_once __DIR__ . '/routes.php';
 
 // Add default middleware
 $app->addRoutingMiddleware();
+$app->add(new BasePathMiddleware($app));
 $app->addErrorMiddleware(true, false, false);
 
 $app->run();

composer.json

@@ -7,6 +7,7 @@
 		"php-di/php-di": "^6.0",
 		"rubellum/slim-blade-view": "^0.1.1",
 		"tuupola/cors-middleware": "^1.1",
+		"selective/basepath": "^0.2.0",
 		"morris/lessql": "^0.4.1",
 		"gettext/gettext": "^4.8",
 		"eluceo/ical": "^0.16.0",

composer.lock

@@ -4,7 +4,7 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "9c7420e77a3f1afb59e00560d5b9081c",
+    "content-hash": "b1fde916a45ad371e89da8c603362c0c",
     "packages": [
         {
             "name": "doctrine/inflector",
@@ -1652,6 +1652,51 @@
             ],
             "time": "2016-03-11T02:32:00+00:00"
         },
+        {
+            "name": "selective/basepath",
+            "version": "0.2.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/selective-php/basepath.git",
+                "reference": "58566c248279a0035012c393b669619ff3a140ee"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/selective-php/basepath/zipball/58566c248279a0035012c393b669619ff3a140ee",
+                "reference": "58566c248279a0035012c393b669619ff3a140ee",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^7.1",
+                "psr/http-server-middleware": "^1.0"
+            },
+            "require-dev": {
+                "overtrue/phplint": "^1.1",
+                "phpstan/phpstan-shim": "^0.11",
+                "phpunit/phpunit": "^7",
+                "slim/psr7": "^0.6.0",
+                "slim/slim": "^4.3",
+                "squizlabs/php_codesniffer": "^3.4"
+            },
+            "type": "library",
+            "autoload": {
+                "psr-4": {
+                    "Selective\\BasePath\\": "src"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "description": "A URL base path detector for Slim 4",
+            "homepage": "https://github.com/selective-php/basepath",
+            "keywords": [
+                "basepath",
+                "slim",
+                "slim4"
+            ],
+            "time": "2019-11-24T21:59:39+00:00"
+        },
         {
             "name": "slim/http",
             "version": "1.0.0",