diff --git a/composer.json b/composer.json
index b11c6c1d..a67cbe79 100644
--- a/composer.json
+++ b/composer.json
@@ -9,8 +9,9 @@
     ],
     "require": {
         "php": ">=7.0 <9.0",
+        "filp/whoops": "^2.14",
         "foxy/foxy": "^1.0.0",
-        "katzgrau/klogger": "1.0.*",
+        "katzgrau/klogger": "~1.0",
         "smarty/smarty": "~3.1.33",
         "voku/simple-cache": "4.*"
     },
diff --git a/composer.lock b/composer.lock
index e3696a9f..49ec01d5 100644
--- a/composer.lock
+++ b/composer.lock
@@ -4,8 +4,79 @@
         "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
         "This file is @generated automatically"
     ],
-    "content-hash": "40f0311ec28386f8c283291d768ba4bb",
+    "content-hash": "adba64a31c2fda3c0e61414e5166f2a9",
     "packages": [
+        {
+            "name": "filp/whoops",
+            "version": "2.14.5",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/filp/whoops.git",
+                "reference": "a63e5e8f26ebbebf8ed3c5c691637325512eb0dc"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/filp/whoops/zipball/a63e5e8f26ebbebf8ed3c5c691637325512eb0dc",
+                "reference": "a63e5e8f26ebbebf8ed3c5c691637325512eb0dc",
+                "shasum": ""
+            },
+            "require": {
+                "php": "^5.5.9 || ^7.0 || ^8.0",
+                "psr/log": "^1.0.1 || ^2.0 || ^3.0"
+            },
+            "require-dev": {
+                "mockery/mockery": "^0.9 || ^1.0",
+                "phpunit/phpunit": "^4.8.36 || ^5.7.27 || ^6.5.14 || ^7.5.20 || ^8.5.8 || ^9.3.3",
+                "symfony/var-dumper": "^2.6 || ^3.0 || ^4.0 || ^5.0"
+            },
+            "suggest": {
+                "symfony/var-dumper": "Pretty print complex values better with var-dumper available",
+                "whoops/soap": "Formats errors as SOAP responses"
+            },
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "2.7-dev"
+                }
+            },
+            "autoload": {
+                "psr-4": {
+                    "Whoops\\": "src/Whoops/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Filipe Dobreira",
+                    "homepage": "https://github.com/filp",
+                    "role": "Developer"
+                }
+            ],
+            "description": "php error handling for cool kids",
+            "homepage": "https://filp.github.io/whoops/",
+            "keywords": [
+                "error",
+                "exception",
+                "handling",
+                "library",
+                "throwable",
+                "whoops"
+            ],
+            "support": {
+                "issues": "https://github.com/filp/whoops/issues",
+                "source": "https://github.com/filp/whoops/tree/2.14.5"
+            },
+            "funding": [
+                {
+                    "url": "https://github.com/denis-sokolov",
+                    "type": "github"
+                }
+            ],
+            "time": "2022-01-07T12:00:00+00:00"
+        },
         {
             "name": "foxy/foxy",
             "version": "v1.1.2",
@@ -82,21 +153,21 @@
         },
         {
             "name": "katzgrau/klogger",
-            "version": "1.0.0",
+            "version": "1.2.1",
             "source": {
                 "type": "git",
-                "url": "https://github.com/katzgrau/klogger.git",
-                "reference": "46cdd92a9b4a8443120cc955bf831450cb274813"
+                "url": "https://github.com/katzgrau/KLogger.git",
+                "reference": "a4ed373fa8a214aa4ae7aa4f221fe2c6ce862ef1"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/katzgrau/klogger/zipball/46cdd92a9b4a8443120cc955bf831450cb274813",
-                "reference": "46cdd92a9b4a8443120cc955bf831450cb274813",
+                "url": "https://api.github.com/repos/katzgrau/KLogger/zipball/a4ed373fa8a214aa4ae7aa4f221fe2c6ce862ef1",
+                "reference": "a4ed373fa8a214aa4ae7aa4f221fe2c6ce862ef1",
                 "shasum": ""
             },
             "require": {
                 "php": ">=5.3",
-                "psr/log": "1.0.0"
+                "psr/log": "^1.0.0"
             },
             "require-dev": {
                 "phpunit/phpunit": "4.0.*"
@@ -115,15 +186,13 @@
                 "MIT"
             ],
             "authors": [
-                {
-                    "name": "Dan Horrigan",
-                    "email": "dan@dhorrigan.com",
-                    "homepage": "http://dhorrigan.com",
-                    "role": "Lead Developer"
-                },
                 {
                     "name": "Kenny Katzgrau",
                     "email": "katzgrau@gmail.com"
+                },
+                {
+                    "name": "Dan Horrigan",
+                    "email": "dan@dhorrigan.com"
                 }
             ],
             "description": "A Simple Logging Class",
@@ -131,29 +200,37 @@
                 "logging"
             ],
             "support": {
-                "issues": "https://github.com/katzgrau/klogger/issues",
-                "source": "https://github.com/katzgrau/klogger/tree/1.0.0"
+                "issues": "https://github.com/katzgrau/KLogger/issues",
+                "source": "https://github.com/katzgrau/KLogger/tree/master"
             },
-            "time": "2014-03-20T02:36:36+00:00"
+            "time": "2016-11-07T19:29:14+00:00"
         },
         {
             "name": "psr/log",
-            "version": "1.0.0",
+            "version": "1.1.4",
             "source": {
                 "type": "git",
                 "url": "https://github.com/php-fig/log.git",
-                "reference": "fe0936ee26643249e916849d48e3a51d5f5e278b"
+                "reference": "d49695b909c3b7628b6289db5479a1c204601f11"
             },
             "dist": {
                 "type": "zip",
-                "url": "https://api.github.com/repos/php-fig/log/zipball/fe0936ee26643249e916849d48e3a51d5f5e278b",
-                "reference": "fe0936ee26643249e916849d48e3a51d5f5e278b",
+                "url": "https://api.github.com/repos/php-fig/log/zipball/d49695b909c3b7628b6289db5479a1c204601f11",
+                "reference": "d49695b909c3b7628b6289db5479a1c204601f11",
                 "shasum": ""
             },
+            "require": {
+                "php": ">=5.3.0"
+            },
             "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "1.1.x-dev"
+                }
+            },
             "autoload": {
-                "psr-0": {
-                    "Psr\\Log\\": ""
+                "psr-4": {
+                    "Psr\\Log\\": "Psr/Log/"
                 }
             },
             "notification-url": "https://packagist.org/downloads/",
@@ -163,20 +240,20 @@
             "authors": [
                 {
                     "name": "PHP-FIG",
-                    "homepage": "http://www.php-fig.org/"
+                    "homepage": "https://www.php-fig.org/"
                 }
             ],
             "description": "Common interface for logging libraries",
+            "homepage": "https://github.com/php-fig/log",
             "keywords": [
                 "log",
                 "psr",
                 "psr-3"
             ],
             "support": {
-                "issues": "https://github.com/php-fig/log/issues",
-                "source": "https://github.com/php-fig/log/tree/1.0.0"
+                "source": "https://github.com/php-fig/log/tree/1.1.4"
             },
-            "time": "2012-12-21T11:40:51+00:00"
+            "time": "2021-05-03T11:20:27+00:00"
         },
         {
             "name": "psr/simple-cache",
diff --git a/serendipity_config.inc.php b/serendipity_config.inc.php
index d6c9d6b1..ce3c01fd 100644
--- a/serendipity_config.inc.php
+++ b/serendipity_config.inc.php
@@ -68,6 +68,7 @@ if ($serendipity['production']) {
 
 if ($serendipity['production'] !== true) {
     @ini_set('display_errors', 'on');
+    @ini_set('display_startup_errors', 'on');
 }
 
 // The serendipity errorhandler string
@@ -243,6 +244,13 @@ if (function_exists('get_include_path')) {
 
 require_once("vendor/autoload.php");
 
+
+if ($serendipity['production'] !== true) {
+    $whoops = new \Whoops\Run;
+    $whoops->pushHandler(new \Whoops\Handler\PrettyPageHandler);
+    $whoops->register();
+}
+
 $new_include = ($serendipity['use_PEAR'] ? $old_include . PATH_SEPARATOR : '')
              . S9Y_INCLUDE_PATH . 'bundled-libs/' . PATH_SEPARATOR
              . $serendipity['serendipityPath'] . PATH_SEPARATOR