diff --git a/system/src/Grav/Common/Assets/Pipeline.php b/system/src/Grav/Common/Assets/Pipeline.php
index b009585c8..0470aeecc 100644
--- a/system/src/Grav/Common/Assets/Pipeline.php
+++ b/system/src/Grav/Common/Assets/Pipeline.php
@@ -60,7 +60,7 @@ class Pipeline extends PropertyObject
      * The closure will receive as the only parameter a string with the path/URL of the asset and
      * it should return the content of the asset file as a string.
      *
-     * @var \Closure
+     * @var \Closure|null
      */
     protected $fetch_command;
 
diff --git a/system/src/Grav/Common/Data/Blueprint.php b/system/src/Grav/Common/Data/Blueprint.php
index 481a1b3fa..f819010b8 100644
--- a/system/src/Grav/Common/Data/Blueprint.php
+++ b/system/src/Grav/Common/Data/Blueprint.php
@@ -20,12 +20,13 @@ class Blueprint extends BlueprintForm
     /** @var string */
     protected $context = 'blueprints://';
 
+    /** @var string|null */
     protected $scope;
 
-    /** @var BlueprintSchema */
+    /** @var BlueprintSchema|null */
     protected $blueprintSchema;
 
-    /** @var object */
+    /** @var object|null */
     protected $object;
 
     /** @var array|null */
@@ -40,11 +41,17 @@ class Blueprint extends BlueprintForm
         }
     }
 
+    /**
+     * @param string $scope
+     */
     public function setScope($scope)
     {
         $this->scope = $scope;
     }
 
+    /**
+     * @param object $object
+     */
     public function setObject($object)
     {
         $this->object = $object;
@@ -232,6 +239,10 @@ class Blueprint extends BlueprintForm
         return $this->blueprintSchema;
     }
 
+    /**
+     * @param string $name
+     * @param callable $callable
+     */
     public function addDynamicHandler(string $name, callable $callable): void
     {
         $this->handlers[$name] = $callable;
@@ -259,7 +270,7 @@ class Blueprint extends BlueprintForm
 
     /**
      * @param string $filename
-     * @return string
+     * @return array
      */
     protected function loadFile($filename)
     {
@@ -420,6 +431,11 @@ class Blueprint extends BlueprintForm
         }
     }
 
+    /**
+     * @param array $field
+     * @param string $property
+     * @param mixed $value
+     */
     protected function addPropertyRecursive(array &$field, $property, $value)
     {
         if (\is_array($value) && isset($field[$property]) && \is_array($field[$property])) {
diff --git a/system/src/Grav/Common/Data/Data.php b/system/src/Grav/Common/Data/Data.php
index 3823fda04..e8f6b1929 100644
--- a/system/src/Grav/Common/Data/Data.php
+++ b/system/src/Grav/Common/Data/Data.php
@@ -13,7 +13,6 @@ use RocketTheme\Toolbox\ArrayTraits\Countable;
 use RocketTheme\Toolbox\ArrayTraits\Export;
 use RocketTheme\Toolbox\ArrayTraits\ExportInterface;
 use RocketTheme\Toolbox\ArrayTraits\NestedArrayAccessWithGetters;
-use RocketTheme\Toolbox\File\File;
 use RocketTheme\Toolbox\File\FileInterface;
 
 class Data implements DataInterface, \ArrayAccess, \Countable, \JsonSerializable, ExportInterface
@@ -26,10 +25,10 @@ class Data implements DataInterface, \ArrayAccess, \Countable, \JsonSerializable
     /** @var array */
     protected $items;
 
-    /** @var Blueprint */
+    /** @var Blueprint|null */
     protected $blueprints;
 
-    /** @var File */
+    /** @var FileInterface|null */
     protected $storage;
 
     /**
@@ -281,7 +280,7 @@ class Data implements DataInterface, \ArrayAccess, \Countable, \JsonSerializable
      * Set or get the data storage.
      *
      * @param FileInterface|null $storage Optionally enter a new storage.
-     * @return FileInterface
+     * @return FileInterface|null
      */
     public function file(FileInterface $storage = null)
     {
diff --git a/system/src/Grav/Common/Debugger.php b/system/src/Grav/Common/Debugger.php
index bc6271b73..de8b65635 100644
--- a/system/src/Grav/Common/Debugger.php
+++ b/system/src/Grav/Common/Debugger.php
@@ -26,7 +26,6 @@ use DebugBar\DataCollector\RequestDataCollector;
 use DebugBar\DataCollector\TimeDataCollector;
 use DebugBar\DebugBar;
 use DebugBar\JavascriptRenderer;
-use DebugBar\StandardDebugBar;
 use Grav\Common\Config\Config;
 use Grav\Common\Processors\ProcessorInterface;
 use Grav\Common\Twig\TwigClockworkDataSource;
@@ -45,19 +44,19 @@ class Debugger
     /** @var static */
     protected static $instance;
 
-    /** @var Grav $grav */
+    /** @var Grav|null */
     protected $grav;
 
-    /** @var Config $config */
+    /** @var Config|null */
     protected $config;
 
-    /** @var JavascriptRenderer $renderer */
+    /** @var JavascriptRenderer|null */
     protected $renderer;
 
-    /** @var StandardDebugBar $debugbar */
+    /** @var DebugBar|null */
     protected $debugbar;
 
-    /** @var Clockwork */
+    /** @var Clockwork|null */
     protected $clockwork;
 
     /** @var bool */
@@ -68,18 +67,22 @@ class Debugger
     /** @var array */
     protected $timers = [];
 
-    /** @var array $deprecations */
+    /** @var array */
     protected $deprecations = [];
 
     /** @var callable|null */
     protected $errorHandler;
 
+    /** @var float */
     protected $requestTime;
+
+    /** @var float */
     protected $currentTime;
 
     /** @var int */
     protected $profiling = 0;
 
+    /** @var bool */
     protected $censored = false;
 
     /**
@@ -447,7 +450,7 @@ class Debugger
      *
      * @param string $name
      *
-     * @return DataCollectorInterface
+     * @return DataCollectorInterface|null
      * @throws \DebugBar\DebugBarException
      */
     public function getCollector($name)
diff --git a/system/src/Grav/Common/File/CompiledFile.php b/system/src/Grav/Common/File/CompiledFile.php
index 45ffb8fde..591e804da 100644
--- a/system/src/Grav/Common/File/CompiledFile.php
+++ b/system/src/Grav/Common/File/CompiledFile.php
@@ -17,7 +17,7 @@ trait CompiledFile
      * Get/set parsed file contents.
      *
      * @param mixed $var
-     * @return string
+     * @return string|array
      */
     public function content($var = null)
     {
diff --git a/system/src/Grav/Common/File/CompiledJsonFile.php b/system/src/Grav/Common/File/CompiledJsonFile.php
index d73e817b2..8d34c5c9d 100644
--- a/system/src/Grav/Common/File/CompiledJsonFile.php
+++ b/system/src/Grav/Common/File/CompiledJsonFile.php
@@ -20,7 +20,7 @@ class CompiledJsonFile extends JsonFile
      *
      * @param string $var
      * @param bool $assoc
-     * @return array mixed
+     * @return array
      */
     protected function decode($var, $assoc = true)
     {
diff --git a/system/src/Grav/Common/GPM/GPM.php b/system/src/Grav/Common/GPM/GPM.php
index d6a97b52b..ae571198d 100644
--- a/system/src/Grav/Common/GPM/GPM.php
+++ b/system/src/Grav/Common/GPM/GPM.php
@@ -128,7 +128,7 @@ class GPM extends Iterator
     /**
      * Return the instance of a specific Plugin
      * @param  string $slug The slug of the Plugin
-     * @return Local\Package The instance of the Plugin
+     * @return Local\Package|null The instance of the Plugin
      */
     public function getInstalledPlugin($slug)
     {
@@ -162,7 +162,7 @@ class GPM extends Iterator
     /**
      * Return the instance of a specific Theme
      * @param  string $slug The slug of the Theme
-     * @return Local\Package The instance of the Theme
+     * @return Local\Package|null The instance of the Theme
      */
     public function getInstalledTheme($slug)
     {
diff --git a/system/src/Grav/Common/GPM/Licenses.php b/system/src/Grav/Common/GPM/Licenses.php
index 4b9bc8143..171743a46 100644
--- a/system/src/Grav/Common/GPM/Licenses.php
+++ b/system/src/Grav/Common/GPM/Licenses.php
@@ -41,6 +41,7 @@ class Licenses
     public static function set($slug, $license)
     {
         $licenses = self::getLicenseFile();
+        /** @var array $data */
         $data = (array)$licenses->content();
         $slug = strtolower($slug);
 
@@ -74,6 +75,7 @@ class Licenses
     public static function get($slug = null)
     {
         $licenses = self::getLicenseFile();
+        /** @var array $data */
         $data = (array)$licenses->content();
         $licenses->free();
         $slug = strtolower($slug);
diff --git a/system/src/Grav/Common/Helpers/Truncator.php b/system/src/Grav/Common/Helpers/Truncator.php
index 6447343b5..db3dbe2a6 100644
--- a/system/src/Grav/Common/Helpers/Truncator.php
+++ b/system/src/Grav/Common/Helpers/Truncator.php
@@ -162,6 +162,7 @@ class Truncator
      */
     private static function removeProceedingNodes($domNode, $topNode)
     {
+        /** @var DOMNode|null $nextNode */
         $nextNode = $domNode->nextSibling;
 
         if ($nextNode !== null) {
diff --git a/system/src/Grav/Common/Inflector.php b/system/src/Grav/Common/Inflector.php
index f70d1f931..5643a1f57 100644
--- a/system/src/Grav/Common/Inflector.php
+++ b/system/src/Grav/Common/Inflector.php
@@ -42,7 +42,7 @@ class Inflector
      * @param string $word  English noun to pluralize
      * @param int    $count The count
      *
-     * @return string Plural noun
+     * @return string|false Plural noun
      */
     public static function pluralize($word, $count = 2)
     {
diff --git a/system/src/Grav/Common/Iterator.php b/system/src/Grav/Common/Iterator.php
index 6664481b9..4e1aa20e9 100644
--- a/system/src/Grav/Common/Iterator.php
+++ b/system/src/Grav/Common/Iterator.php
@@ -133,7 +133,7 @@ class Iterator implements \ArrayAccess, \Iterator, \Countable, \Serializable
     /**
      * @param mixed $needle Searched value.
      *
-     * @return string|bool  Key if found, otherwise false.
+     * @return string|int|false  Key if found, otherwise false.
      */
     public function indexOf($needle)
     {
diff --git a/system/src/Grav/Common/Language/Language.php b/system/src/Grav/Common/Language/Language.php
index f4a08c448..450929576 100644
--- a/system/src/Grav/Common/Language/Language.php
+++ b/system/src/Grav/Common/Language/Language.php
@@ -149,7 +149,7 @@ class Language
      *
      * @param string $lang
      *
-     * @return bool
+     * @return string|bool
      */
     public function setDefault($lang)
     {
diff --git a/system/src/Grav/Common/Page/Markdown/Excerpts.php b/system/src/Grav/Common/Page/Markdown/Excerpts.php
index 9ce1898b2..7585ac639 100644
--- a/system/src/Grav/Common/Page/Markdown/Excerpts.php
+++ b/system/src/Grav/Common/Page/Markdown/Excerpts.php
@@ -12,6 +12,7 @@ namespace Grav\Common\Page\Markdown;
 use Grav\Common\Grav;
 use Grav\Common\Page\Interfaces\PageInterface;
 use Grav\Common\Page\Medium\Link;
+use Grav\Common\Page\Pages;
 use Grav\Common\Uri;
 use Grav\Common\Page\Medium\Medium;
 use Grav\Common\Utils;
@@ -20,7 +21,7 @@ use RocketTheme\Toolbox\ResourceLocator\UniformResourceLocator;
 
 class Excerpts
 {
-    /** @var PageInterface */
+    /** @var PageInterface|null */
     protected $page;
     /** @var array */
     protected $config;
diff --git a/system/src/Grav/Common/Page/Medium/AbstractMedia.php b/system/src/Grav/Common/Page/Medium/AbstractMedia.php
index f67cd650e..c107e4d0f 100644
--- a/system/src/Grav/Common/Page/Medium/AbstractMedia.php
+++ b/system/src/Grav/Common/Page/Medium/AbstractMedia.php
@@ -28,6 +28,7 @@ abstract class AbstractMedia implements ExportInterface, MediaCollectionInterfac
     use Export;
 
     protected $items = [];
+    /** @var string */
     protected $path;
     protected $images = [];
     protected $videos = [];
@@ -150,7 +151,7 @@ abstract class AbstractMedia implements ExportInterface, MediaCollectionInterfac
 
     /**
      * @param string $name
-     * @param MediaObjectInterface $file
+     * @param MediaObjectInterface|null $file
      */
     public function add($name, $file)
     {
diff --git a/system/src/Grav/Common/Page/Medium/ImageMedium.php b/system/src/Grav/Common/Page/Medium/ImageMedium.php
index f04502521..4684c63b8 100644
--- a/system/src/Grav/Common/Page/Medium/ImageMedium.php
+++ b/system/src/Grav/Common/Page/Medium/ImageMedium.php
@@ -22,7 +22,7 @@ class ImageMedium extends Medium
     protected $thumbnailTypes = ['page', 'media', 'default'];
 
     /**
-     * @var ImageFile
+     * @var ImageFile|null
      */
     protected $image;
 
@@ -643,7 +643,7 @@ class ImageMedium extends Medium
     /**
      * Return the image higher quality version
      *
-     * @return ImageMedium the alternative version with higher quality
+     * @return Medium|ImageMedium the alternative version with higher quality
      */
     public function higherQualityAlternative()
     {
diff --git a/system/src/Grav/Common/Page/Medium/Medium.php b/system/src/Grav/Common/Page/Medium/Medium.php
index 951b307f3..498bcdc43 100644
--- a/system/src/Grav/Common/Page/Medium/Medium.php
+++ b/system/src/Grav/Common/Page/Medium/Medium.php
@@ -479,7 +479,7 @@ class Medium extends Data implements RenderableInterface, MediaObjectInterface
      *
      * @param string $mode
      *
-     * @return $this|null
+     * @return self|null
      */
     public function display($mode = 'source')
     {
@@ -648,7 +648,7 @@ class Medium extends Data implements RenderableInterface, MediaObjectInterface
     /**
      * Get the thumbnail Medium object
      *
-     * @return ThumbnailImageMedium
+     * @return ThumbnailImageMedium|null
      */
     protected function getThumbnail()
     {
diff --git a/system/src/Grav/Common/Page/Medium/ParsedownHtmlTrait.php b/system/src/Grav/Common/Page/Medium/ParsedownHtmlTrait.php
index 1d9ceb6ef..4b4714069 100644
--- a/system/src/Grav/Common/Page/Medium/ParsedownHtmlTrait.php
+++ b/system/src/Grav/Common/Page/Medium/ParsedownHtmlTrait.php
@@ -15,7 +15,7 @@ use Grav\Common\Page\Markdown\Excerpts;
 trait ParsedownHtmlTrait
 {
     /**
-     * @var \Grav\Common\Markdown\Parsedown
+     * @var \Grav\Common\Markdown\Parsedown|null
      */
     protected $parsedown;
 
diff --git a/system/src/Grav/Common/Page/Medium/ThumbnailImageMedium.php b/system/src/Grav/Common/Page/Medium/ThumbnailImageMedium.php
index 252116835..71ab56835 100644
--- a/system/src/Grav/Common/Page/Medium/ThumbnailImageMedium.php
+++ b/system/src/Grav/Common/Page/Medium/ThumbnailImageMedium.php
@@ -12,7 +12,7 @@ namespace Grav\Common\Page\Medium;
 class ThumbnailImageMedium extends ImageMedium
 {
     /**
-     * @var Medium
+     * @var Medium|null
      */
     public $parent = null;
 
@@ -67,7 +67,7 @@ class ThumbnailImageMedium extends ImageMedium
      *
      * @param string $mode
      *
-     * @return $this
+     * @return array|Link|Medium
      */
     public function display($mode = 'source')
     {
@@ -79,7 +79,7 @@ class ThumbnailImageMedium extends ImageMedium
      *
      * @param string $type
      *
-     * @return $this
+     * @return array|Link|Medium
      */
     public function thumbnail($type = 'auto')
     {
@@ -119,7 +119,7 @@ class ThumbnailImageMedium extends ImageMedium
      * @param  string  $method
      * @param  array  $arguments
      * @param  bool $testLinked
-     * @return Medium|Link|array
+     * @return array|Link|Medium
      */
     protected function bubble($method, array $arguments = [], $testLinked = true)
     {
diff --git a/system/src/Grav/Common/Page/Medium/VideoMedium.php b/system/src/Grav/Common/Page/Medium/VideoMedium.php
index dff4bd34e..730558f82 100644
--- a/system/src/Grav/Common/Page/Medium/VideoMedium.php
+++ b/system/src/Grav/Common/Page/Medium/VideoMedium.php
@@ -98,7 +98,7 @@ class VideoMedium extends Medium
     /**
      * Allows ability to set the preload option
      *
-     * @param null $status
+     * @param string|null $status
      * @return $this
      */
     public function preload($status = null)
diff --git a/system/src/Grav/Common/Page/Page.php b/system/src/Grav/Common/Page/Page.php
index 4bb2461a9..2da55856a 100644
--- a/system/src/Grav/Common/Page/Page.php
+++ b/system/src/Grav/Common/Page/Page.php
@@ -19,6 +19,7 @@ use Grav\Common\Language\Language;
 use Grav\Common\Markdown\Parsedown;
 use Grav\Common\Markdown\ParsedownExtra;
 use Grav\Common\Media\Interfaces\MediaCollectionInterface;
+use Grav\Common\Page\Interfaces\PageCollectionInterface;
 use Grav\Common\Page\Interfaces\PageInterface;
 use Grav\Common\Media\Traits\MediaTrait;
 use Grav\Common\Page\Markdown\Excerpts;
@@ -64,7 +65,7 @@ class Page implements PageInterface
     protected $redirect;
     protected $external_url;
     protected $items;
-    /** @var \stdClass */
+    /** @var object|null */
     protected $header;
     protected $frontmatter;
     protected $language;
@@ -1216,8 +1217,8 @@ class Page implements PageInterface
     /**
      * Gets and sets the associated media as found in the page folder.
      *
-     * @param  Media $var Representation of associated media.
-     * @return Media      Representation of associated media.
+     * @param  MediaCollectionInterface|Media $var Representation of associated media.
+     * @return MediaCollectionInterface|Media      Representation of associated media.
      */
     public function media($var = null)
     {
@@ -1376,8 +1377,8 @@ class Page implements PageInterface
      * Gets and sets the cache-control property.  If not set it will return the default value (null)
      * https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Cache-Control for more details on valid options
      *
-     * @param null $var
-     * @return null
+     * @param string|null $var
+     * @return string|null
      */
     public function cacheControl($var = null)
     {
@@ -1829,7 +1830,7 @@ class Page implements PageInterface
     /**
      * Gets and Sets the page raw route
      *
-     * @param null $var
+     * @param string|null $var
      *
      * @return null|string
      */
@@ -1875,7 +1876,7 @@ class Page implements PageInterface
      * Gets the canonical route for this page if its set. If provided it will use
      * that value, else if it's `true` it will use the default route.
      *
-     * @param null $var
+     * @param string|null $var
      *
      * @return bool|string
      */
@@ -2309,7 +2310,7 @@ class Page implements PageInterface
     /**
      * Returns children of this page.
      *
-     * @return Collection
+     * @return PageCollectionInterface|Collection
      */
     public function children()
     {
@@ -2433,7 +2434,7 @@ class Page implements PageInterface
         $routes = Grav::instance()['pages']->routes();
 
         if (isset($routes[$uri_path])) {
-            /** @var PageInterface $child_page */
+            /** @var PageInterface|null $child_page */
             $child_page = $pages->find($uri->route())->parent();
             if ($child_page) {
                 while (!$child_page->root()) {
@@ -2561,7 +2562,7 @@ class Page implements PageInterface
      * @param string|array $params
      * @param bool $pagination
      *
-     * @return Collection
+     * @return PageCollectionInterface|Collection
      * @throws \InvalidArgumentException
      */
     public function collection($params = 'content', $pagination = true)
@@ -2590,7 +2591,7 @@ class Page implements PageInterface
     /**
      * @param string|array $value
      * @param bool $only_published
-     * @return Collection
+     * @return PageCollectionInterface|Collection
      */
     public function evaluate($value, $only_published = true)
     {
diff --git a/system/src/Grav/Common/Scheduler/IntervalTrait.php b/system/src/Grav/Common/Scheduler/IntervalTrait.php
index 821833780..ef309bf3c 100644
--- a/system/src/Grav/Common/Scheduler/IntervalTrait.php
+++ b/system/src/Grav/Common/Scheduler/IntervalTrait.php
@@ -374,7 +374,7 @@ trait IntervalTrait
     /**
      * Validate sequence of cron expression.
      *
-     * @param  int|string  $value
+     * @param  int|string|null  $value
      * @param  int         $min
      * @param  int         $max
      * @return mixed
diff --git a/system/src/Grav/Common/Scheduler/Job.php b/system/src/Grav/Common/Scheduler/Job.php
index 6fcd4a2ea..70b1990e5 100644
--- a/system/src/Grav/Common/Scheduler/Job.php
+++ b/system/src/Grav/Common/Scheduler/Job.php
@@ -37,6 +37,7 @@ class Job
     private $after;
     private $whenOverlapping;
     private $outputMode;
+    /** @var Process|null $process */
     private $process;
     private $successful = false;
     private $backlink;
@@ -73,7 +74,7 @@ class Job
     /**
      * Get the command
      *
-     * @return string
+     * @return \Closure|string
      */
     public function getCommand()
     {
@@ -322,7 +323,6 @@ class Job
      */
     public function finalize()
     {
-        /** @var Process $process */
         $process = $this->process;
 
         if ($process) {
diff --git a/system/src/Grav/Common/Scheduler/Scheduler.php b/system/src/Grav/Common/Scheduler/Scheduler.php
index e2ee7deef..5b214face 100644
--- a/system/src/Grav/Common/Scheduler/Scheduler.php
+++ b/system/src/Grav/Common/Scheduler/Scheduler.php
@@ -126,7 +126,7 @@ class Scheduler
     /**
      * Get a specific Job based on id
      *
-     * @param $jobid
+     * @param string $jobid
      * @return Job|null
      */
     public function getJob($jobid)
diff --git a/system/src/Grav/Common/Security.php b/system/src/Grav/Common/Security.php
index 494be2e13..0aef82cce 100644
--- a/system/src/Grav/Common/Security.php
+++ b/system/src/Grav/Common/Security.php
@@ -116,7 +116,7 @@ class Security
      * return false positives because of it tags all potentially dangerous HTML tags and attributes without looking into
      * their content.
      *
-     * @param string $string The string to run XSS detection logic on
+     * @param string|null $string The string to run XSS detection logic on
      * @return bool|string       Type of XSS vector if the given `$string` may contain XSS, false otherwise.
      *
      * Copies the code from: https://github.com/symphonycms/xssfilter/blob/master/extension.driver.php#L138
diff --git a/system/src/Grav/Common/Session.php b/system/src/Grav/Common/Session.php
index f913810b4..b388e4ea3 100644
--- a/system/src/Grav/Common/Session.php
+++ b/system/src/Grav/Common/Session.php
@@ -118,12 +118,12 @@ class Session extends \Grav\Framework\Session\Session
 
                 /** @var Uri $uri */
                 $uri = $grav['uri'];
-                /** @var Grav\Plugin\Form\Forms $form */
+                /** @var Grav\Plugin\Form\Forms|null $form */
                 $form = $grav['forms']->getActiveForm();
 
                 $sessionField = base64_encode($uri->url);
 
-                /** @var FormFlash $flash */
+                /** @var FormFlash|null $flash */
                 $flash = $form ? $form->getFlash() : null;
                 $object = $flash && method_exists($flash, 'getLegacyFiles') ? [$sessionField => $flash->getLegacyFiles()] : null;
             }
diff --git a/system/src/Grav/Common/Twig/TwigExtension.php b/system/src/Grav/Common/Twig/TwigExtension.php
index 1d6a6c38e..e78790ab3 100644
--- a/system/src/Grav/Common/Twig/TwigExtension.php
+++ b/system/src/Grav/Common/Twig/TwigExtension.php
@@ -251,7 +251,7 @@ class TwigExtension extends AbstractExtension implements GlobalsInterface
     /**
      * Returns array in a random order.
      *
-     * @param  array $original
+     * @param  array|\Traversable $original
      * @param  int   $offset Can be used to return only slice of the array.
      *
      * @return array
@@ -421,7 +421,7 @@ class TwigExtension extends AbstractExtension implements GlobalsInterface
     /**
      * Return ksorted collection.
      *
-     * @param  array $array
+     * @param  array|null $array
      *
      * @return array
      */
@@ -979,9 +979,9 @@ class TwigExtension extends AbstractExtension implements GlobalsInterface
     /**
      * Wrapper for array_intersect() method
      *
-     * @param array $array1
-     * @param array $array2
-     * @return array
+     * @param array|Collection $array1
+     * @param array|Collection $array2
+     * @return array|Collection
      */
     public function arrayIntersectFunc($array1, $array2)
     {
diff --git a/system/src/Grav/Common/Uri.php b/system/src/Grav/Common/Uri.php
index 1ff32a918..b6a1893ae 100644
--- a/system/src/Grav/Common/Uri.php
+++ b/system/src/Grav/Common/Uri.php
@@ -22,10 +22,10 @@ class Uri
 {
     const HOSTNAME_REGEX = '/^(([a-zA-Z0-9]|[a-zA-Z0-9][a-zA-Z0-9\-]*[a-zA-Z0-9])\.)*([A-Za-z0-9]|[A-Za-z0-9][A-Za-z0-9\-]*[A-Za-z0-9])$/';
 
-    /** @var \Grav\Framework\Uri\Uri */
+    /** @var \Grav\Framework\Uri\Uri|null */
     protected static $currentUri;
 
-    /** @var \Grav\Framework\Route\Route */
+    /** @var \Grav\Framework\Route\Route|null */
     protected static $currentRoute;
 
     public $url;
@@ -953,7 +953,7 @@ class Uri
      * @param PageInterface   $page         the current page to use as reference
      * @param string $markdown_url the URL as it was written in the markdown
      * @param string $type         the type of URL, image | link
-     * @param null   $relative     if null, will use system default, if true will use relative links internally
+     * @param bool|null $relative     if null, will use system default, if true will use relative links internally
      *
      * @return string the more friendly formatted url
      */
@@ -1109,7 +1109,7 @@ class Uri
     /**
      * Filters the user info string.
      *
-     * @param string $info The raw user or password.
+     * @param string|null $info The raw user or password.
      * @return string The percent-encoded user or password string.
      */
     public static function filterUserInfo($info)
@@ -1125,7 +1125,7 @@ class Uri
      * will NOT double-encode characters that are already
      * percent-encoded.
      *
-     * @param  string $path The raw uri path.
+     * @param  string|null $path The raw uri path.
      * @return string       The RFC 3986 percent-encoded uri path.
      * @link   http://www.faqs.org/rfcs/rfc3986.html
      */
@@ -1137,7 +1137,7 @@ class Uri
     /**
      * Filters the query string or fragment of a URI.
      *
-     * @param string $query The raw uri query string.
+     * @param string|null $query The raw uri query string.
      * @return string The percent-encoded query string.
      */
     public static function filterQuery($query)
diff --git a/system/src/Grav/Common/User/DataUser/User.php b/system/src/Grav/Common/User/DataUser/User.php
index 64bf0936f..fe247fa4d 100644
--- a/system/src/Grav/Common/User/DataUser/User.php
+++ b/system/src/Grav/Common/User/DataUser/User.php
@@ -103,7 +103,7 @@ class User extends Data implements UserInterface
      */
     public function save()
     {
-        /** @var CompiledYamlFile $file */
+        /** @var CompiledYamlFile|null $file */
         $file = $this->file();
         if (!$file || !$file->filename()) {
             user_error(__CLASS__ . ': calling \$user = new ' . __CLASS__ . "() is deprecated since Grav 1.6, use \$grav['accounts']->load(\$username) or \$grav['accounts']->load('') instead", E_USER_DEPRECATED);
diff --git a/system/src/Grav/Common/User/FlexUser/Group.php b/system/src/Grav/Common/User/FlexUser/Group.php
index 31a5cc655..a2a780170 100644
--- a/system/src/Grav/Common/User/FlexUser/Group.php
+++ b/system/src/Grav/Common/User/FlexUser/Group.php
@@ -97,7 +97,7 @@ class Group extends FlexObject
 
     /**
      * @param mixed $value
-     * @return Access
+     * @return array
      */
     protected function offsetPrepare_access($value): array
     {
@@ -105,7 +105,7 @@ class Group extends FlexObject
     }
 
     /**
-     * @param Access|null $value
+     * @param array|null $value
      * @return array|null
      */
     protected function offsetSerialize_access(?array $value): ?array
diff --git a/system/src/Grav/Common/User/FlexUser/GroupIndex.php b/system/src/Grav/Common/User/FlexUser/GroupIndex.php
index 0eb302989..a292030df 100644
--- a/system/src/Grav/Common/User/FlexUser/GroupIndex.php
+++ b/system/src/Grav/Common/User/FlexUser/GroupIndex.php
@@ -11,6 +11,12 @@ namespace Grav\Common\User\FlexUser;
 
 use Grav\Framework\Flex\FlexIndex;
 
+/**
+ * Class GroupIndex
+ * @package Grav\Common\User\FlexUser
+ *
+ * @method bool|null authorize(string $action, string $scope = null)
+ */
 class GroupIndex extends FlexIndex
 {
 }
diff --git a/system/src/Grav/Common/User/FlexUser/User.php b/system/src/Grav/Common/User/FlexUser/User.php
index 4f17ae9ba..daf47b818 100644
--- a/system/src/Grav/Common/User/FlexUser/User.php
+++ b/system/src/Grav/Common/User/FlexUser/User.php
@@ -15,8 +15,10 @@ use Grav\Common\Page\Media;
 use Grav\Common\Page\Medium\ImageMedium;
 use Grav\Common\Page\Medium\Medium;
 use Grav\Common\Page\Medium\MediumFactory;
+use Grav\Common\Page\Medium\StaticImageMedium;
 use Grav\Common\User\Access;
 use Grav\Common\User\Authentication;
+use Grav\Common\User\Interfaces\UserCollectionInterface;
 use Grav\Common\User\Interfaces\UserInterface;
 use Grav\Common\User\Traits\UserTrait;
 use Grav\Common\Utils;
@@ -465,7 +467,7 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
      * Set or get the data storage.
      *
      * @param FileInterface|null $storage Optionally enter a new storage.
-     * @return FileInterface
+     * @return FileInterface|null
      */
     public function file(FileInterface $storage = null)
     {
@@ -552,7 +554,7 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
     /**
      * Return media object for the User's avatar.
      *
-     * @return ImageMedium|null
+     * @return ImageMedium|StaticImageMedium|null
      * @deprecated 1.6 Use ->getAvatarImage() method instead.
      */
     public function getAvatarMedia()
@@ -644,7 +646,7 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
 
     /**
      * @param mixed $value
-     * @return Access
+     * @return array
      */
     protected function offsetPrepare_access($value): array
     {
@@ -652,7 +654,7 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
     }
 
     /**
-     * @param Access|null $value
+     * @param array|null $value
      * @return array|null
      */
     protected function offsetSerialize_access(?array $value): ?array
@@ -786,7 +788,7 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
     protected function saveUpdatedMedia(): void
     {
         // Upload/delete original sized images.
-        /** @var FormFlashFile $file */
+        /** @var FormFlashFile|null $file */
         foreach ($this->_uploads_original ?? [] as $name => $file) {
             $name = 'original/' . $name;
             if ($file) {
@@ -798,7 +800,7 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
 
         /**
          * @var string $filename
-         * @var UploadedFileInterface $file
+         * @var UploadedFileInterface|null $file
          */
         foreach ($this->getUpdatedMedia() as $filename => $file) {
             if ($file) {
@@ -830,9 +832,9 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
                 continue;
             }
 
-            /** @var Medium $thumbFile */
+            /** @var Medium|null $thumbFile */
             $thumbFile = $resizedMedia[$filename];
-            /** @var Medium $imageFile */
+            /** @var Medium|null $imageFile */
             $imageFile = $originalMedia[$filename] ?? $thumbFile;
             if ($thumbFile) {
                 $list[$filename] = [
@@ -890,14 +892,14 @@ class User extends FlexObject implements UserInterface, MediaManipulationInterfa
     }
 
     /**
-     * @return GroupCollection
+     * @return GroupCollection|GroupIndex
      */
     protected function getUserGroups()
     {
         $grav = Grav::instance();
         $flex = $grav['flex_objects'] ?? null;
 
-        /** @var GroupCollection $groups */
+        /** @var GroupCollection|null $groups */
         $groups = $flex ? $flex->getDirectory('grav-user-groups') : null;
 
         if ($groups) {
diff --git a/system/src/Grav/Common/User/Traits/UserTrait.php b/system/src/Grav/Common/User/Traits/UserTrait.php
index 69d2e7528..049ed8dfe 100644
--- a/system/src/Grav/Common/User/Traits/UserTrait.php
+++ b/system/src/Grav/Common/User/Traits/UserTrait.php
@@ -116,7 +116,7 @@ trait UserTrait
      *
      * Note: if there's no local avatar image for the user, you should call getAvatarUrl() to get the external avatar URL.
      *
-     * @return Medium|null
+     * @return ImageMedium|StaticImageMedium|null
      */
     public function getAvatarImage(): ?Medium
     {
diff --git a/system/src/Grav/Common/Utils.php b/system/src/Grav/Common/Utils.php
index 36864b943..0df0391aa 100644
--- a/system/src/Grav/Common/Utils.php
+++ b/system/src/Grav/Common/Utils.php
@@ -1298,7 +1298,7 @@ abstract class Utils
      * Get a portion of an array (passed by reference) with dot-notation key
      *
      * @param array $array
-     * @param string|int $key
+     * @param string|int|null $key
      * @param null $default
      * @return mixed
      */
@@ -1327,10 +1327,10 @@ abstract class Utils
      * Set portion of array (passed by reference) for a dot-notation key
      * and set the value
      *
-     * @param array      $array
-     * @param string|int $key
-     * @param mixed      $value
-     * @param bool       $merge
+     * @param array $array
+     * @param string|int|null $key
+     * @param mixed $value
+     * @param bool $merge
      *
      * @return mixed
      */
diff --git a/system/src/Grav/Console/Cli/SchedulerCommand.php b/system/src/Grav/Console/Cli/SchedulerCommand.php
index a0068ed6b..64058c120 100644
--- a/system/src/Grav/Console/Cli/SchedulerCommand.php
+++ b/system/src/Grav/Console/Cli/SchedulerCommand.php
@@ -159,7 +159,6 @@ class SchedulerCommand extends ConsoleCommand
         } elseif ($jobid = $this->input->getOption('run')) {
             $io->title('Force Run Job: ' . $jobid);
 
-            /** @var Job $job */
             $job = $scheduler->getJob($jobid);
 
             if ($job) {
diff --git a/system/src/Grav/Console/Gpm/InstallCommand.php b/system/src/Grav/Console/Gpm/InstallCommand.php
index 20a962f2a..a1ac8ba6c 100644
--- a/system/src/Grav/Console/Gpm/InstallCommand.php
+++ b/system/src/Grav/Console/Gpm/InstallCommand.php
@@ -320,7 +320,7 @@ class InstallCommand extends ConsoleCommand
     }
 
     /**
-     * @param Package $package
+     * @param Package|null $package
      * @param bool    $is_update      True if the package is an update
      */
     private function processPackage($package, $is_update = false)
@@ -447,7 +447,7 @@ class InstallCommand extends ConsoleCommand
             } else {
                 $repo_dir = $matches[2];
             }
-            
+
             $paths = (array) $paths;
             foreach ($paths as $repo) {
                 $path = rtrim($repo, '/') . '/' . $repo_dir;
diff --git a/system/src/Grav/Framework/Flex/Pages/FlexPageCollection.php b/system/src/Grav/Framework/Flex/Pages/FlexPageCollection.php
index f601fd0a2..689d2ac39 100644
--- a/system/src/Grav/Framework/Flex/Pages/FlexPageCollection.php
+++ b/system/src/Grav/Framework/Flex/Pages/FlexPageCollection.php
@@ -106,7 +106,7 @@ class FlexPageCollection extends FlexCollection
      *
      * @param  string $path
      *
-     * @return PageInterface|null The next item.
+     * @return PageInterface|false The next item.
      */
     public function nextSibling($path)
     {
@@ -119,7 +119,7 @@ class FlexPageCollection extends FlexCollection
      * @param  string  $path
      * @param  int $direction either -1 or +1
      *
-     * @return PageInterface|null    The sibling item.
+     * @return PageInterface|false    The sibling item.
      */
     public function adjacentSibling($path, $direction = 1)
     {
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php
index 9a9e717b3..45b70fc98 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php
@@ -1098,9 +1098,27 @@ trait PageLegacyTrait
      * @return CacheInterface
      */
     abstract public function getCache(string $namespace = null);
+
+    /**
+     * @param PageInterface|null $var
+     * @return PageInterface|FlexObjectInterface|null
+     */
     abstract public function parent(PageInterface $var = null);
+
     abstract public function getFlexDirectory(): FlexDirectory;
+
     abstract protected function exists(): bool;
+
+    /**
+     * @return string|null
+     */
     abstract protected function getStorageFolder();
+
+    /**
+     * @param string $property
+     * @param mixed $var
+     * @param callable $filter
+     * @return mixed|null
+     */
     abstract protected function loadHeaderProperty(string $property, $var, callable $filter);
 }
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
index 48b2daca5..3363c56c2 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
@@ -15,6 +15,7 @@ use Grav\Common\Page\Interfaces\PageCollectionInterface;
 use Grav\Common\Page\Interfaces\PageInterface;
 use Grav\Common\Page\Pages;
 use Grav\Common\Uri;
+use Grav\Framework\Flex\Interfaces\FlexObjectInterface;
 use RocketTheme\Toolbox\ResourceLocator\UniformResourceLocator;
 
 /**
@@ -377,7 +378,7 @@ trait PageRoutableTrait
      * Gets and Sets the parent object for this page
      *
      * @param  PageInterface|null $var the parent page object
-     * @return PageInterface|null the parent page object if it exists.
+     * @return PageInterface|FlexObjectInterface|null the parent page object if it exists.
      */
     public function parent(PageInterface $var = null)
     {
diff --git a/tests/phpstan/phpstan.neon b/tests/phpstan/phpstan.neon
index dca9776e7..413a3030f 100644
--- a/tests/phpstan/phpstan.neon
+++ b/tests/phpstan/phpstan.neon
@@ -115,3 +115,9 @@ parameters:
         -
             message: '#deprecated class#'
             path: 'system/src/Grav/Framework/Uri/Uri.php'
+        -
+            message: '#Method Symfony\\Contracts\\EventDispatcher\\EventDispatcherInterface::dispatch#'
+            path: 'system/src/Grav/Common/Grav.php'
+        - '#Call to deprecated method stopPropagation\(\) of class Symfony\\Component\\EventDispatcher\\Event#'
+        - '#Parameter \#2 \$listener of method Symfony\\Component\\EventDispatcher\\EventDispatcher::addListener\(\)#'
+        - '#Parameter \#2 \$listener of method Symfony\\Component\\EventDispatcher\\EventDispatcher::removeListener\(\)#'