diff --git a/system/src/Grav/Common/Filesystem/Folder.php b/system/src/Grav/Common/Filesystem/Folder.php
index 1f5575d51..fecf8a448 100644
--- a/system/src/Grav/Common/Filesystem/Folder.php
+++ b/system/src/Grav/Common/Filesystem/Folder.php
@@ -487,7 +487,7 @@ abstract class Folder
     /**
      * Does a directory contain children
      *
-     * @param $dir
+     * @param string $directory
      * @return bool
      */
     public static function hasChildren($directory) {
diff --git a/system/src/Grav/Common/Flex/Types/Pages/PageObject.php b/system/src/Grav/Common/Flex/Types/Pages/PageObject.php
index a845e4336..a7f003eb0 100644
--- a/system/src/Grav/Common/Flex/Types/Pages/PageObject.php
+++ b/system/src/Grav/Common/Flex/Types/Pages/PageObject.php
@@ -222,7 +222,6 @@ class PageObject extends FlexPageObject
 
     /**
      * @param array $variables
-     * @return array
      */
     protected function onAfterSave(array $variables): void
     {
diff --git a/system/src/Grav/Framework/File/AbstractFile.php b/system/src/Grav/Framework/File/AbstractFile.php
index 71298af71..a2eda44c7 100644
--- a/system/src/Grav/Framework/File/AbstractFile.php
+++ b/system/src/Grav/Framework/File/AbstractFile.php
@@ -281,6 +281,9 @@ class AbstractFile implements FileInterface
             } else {
                 // Support for symlinks.
                 $realpath = is_link($filepath) ? realpath($filepath) : $filepath;
+                if ($realpath === false) {
+                    throw new \RuntimeException('Failed to save file ' . $filepath);
+                }
 
                 // Create file with a temporary name and rename it to make the save action atomic.
                 $tmp = $this->tempname($realpath);
diff --git a/system/src/Grav/Framework/Flex/Pages/FlexPageObject.php b/system/src/Grav/Framework/Flex/Pages/FlexPageObject.php
index 92d220ae0..8ae157ed1 100644
--- a/system/src/Grav/Framework/Flex/Pages/FlexPageObject.php
+++ b/system/src/Grav/Framework/Flex/Pages/FlexPageObject.php
@@ -444,7 +444,7 @@ class FlexPageObject extends FlexObject implements PageInterface, MediaManipulat
     }
 
     /**
-     * @return UserCollectionInterface|FlexCollectionInterface|null
+     * @return UserCollectionInterface|null
      * @internal
      */
     protected function loadAccounts()
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php
index da83545f3..852b64991 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php
@@ -230,6 +230,6 @@ trait PageAuthorsTrait
     }
 
     abstract public function getNestedProperty($property, $default = null, $separator = null);
-    abstract protected function loadAccounts();
 
+    abstract protected function loadAccounts();
 }
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
index d06a30f66..4e4237f10 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
@@ -28,7 +28,7 @@ trait PageRoutableTrait
 
     /** @var string */
     private $_route;
-    /** @var string */
+    /** @var string|null */
     private $_path;
 
     /**
diff --git a/system/src/Grav/Framework/Flex/Storage/AbstractFilesystemStorage.php b/system/src/Grav/Framework/Flex/Storage/AbstractFilesystemStorage.php
index a829b3587..c2f3a734f 100644
--- a/system/src/Grav/Framework/Flex/Storage/AbstractFilesystemStorage.php
+++ b/system/src/Grav/Framework/Flex/Storage/AbstractFilesystemStorage.php
@@ -34,8 +34,8 @@ abstract class AbstractFilesystemStorage implements FlexStorageInterface
     protected $dataFormatter;
     /** @var string */
     protected $keyField = 'storage_key';
-    /** @var string */
-    protected $keyLen = '32';
+    /** @var int */
+    protected $keyLen = 32;
 
     /**
      * @return bool
diff --git a/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php b/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php
index b4120749a..3f856ef5f 100644
--- a/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php
+++ b/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php
@@ -242,7 +242,7 @@ trait FlexMediaTrait
             $locator->clearCache($targetFile);
         }
 
-        $fileParts  = $filesystem->pathinfo($basename);
+        $fileParts = (array)$filesystem->pathinfo($basename);
 
         if (!file_exists($targetPath)) {
             return;
diff --git a/system/src/Grav/Framework/Session/Session.php b/system/src/Grav/Framework/Session/Session.php
index 67df237f0..ca0e05f4a 100644
--- a/system/src/Grav/Framework/Session/Session.php
+++ b/system/src/Grav/Framework/Session/Session.php
@@ -266,7 +266,7 @@ class Session implements SessionInterface
             return $this;
         }
 
-        // TODO: session_create_id() segfaults in PHP 7.3 (PHP bug #73461)
+        // TODO: session_create_id() segfaults in PHP 7.3 (PHP bug #73461), remove phpstan rule when fixing this one.
         $newId = 0; // session_create_id();
 
         // Set destroyed timestamp for the old session as well as pointer to the new id.
diff --git a/tests/phpstan/phpstan.neon b/tests/phpstan/phpstan.neon
index 7acc2c2bc..ba2bf1c68 100644
--- a/tests/phpstan/phpstan.neon
+++ b/tests/phpstan/phpstan.neon
@@ -25,6 +25,10 @@ parameters:
     ignoreErrors:
 
         # FIXME: Bugs that need to be fixed
+        # FIXME: PHP 7.3 bug workaround
+        -
+            message: '#If condition is always false.#'
+            path: 'system/src/Grav/Framework/Session/Session.php'
 
         # TODO: Errors that needs some more thinking (bad design?)
         - '#Access to an undefined property RocketTheme\\Toolbox\\Event\\Event::#'
@@ -90,8 +94,11 @@ parameters:
             message: '#unknown class (Memcache|Memcached|Redis|RedisException)#'
             path: 'system/src/Grav/Common/Cache.php'
         -
-            message: '#on an unknown class Collator#'
+            message: '#unknown class Collator#'
             path: 'system/src/Grav/Common/Page/Pages.php'
+        -
+            message: '#unknown class Collator#'
+            path: 'system/src/Grav/Common/Flex/Types/Pages/PageCollection.php'
         -
             message: '#Ternary operator condition is always true#'
             path: 'system/src/Grav/Framework/Cache/AbstractCache.php'
@@ -121,6 +128,15 @@ parameters:
         -
             message: '#Call to deprecated method \w+\(\) of class Grav\\Framework\\Flex\\FlexObject#'
             path: 'system/src/Grav/Framework/Flex/FlexObject.php'
+        -
+            message: '#Call to deprecated method \w+\(\) of class Grav\\Framework\\Flex\\FlexIndex#'
+            path: 'system/src/Grav/Framework/Flex/FlexIndex.php'
+        -
+            message: '#Call to deprecated method \w+\(\) of class Grav\\Framework\\Flex\\FlexCollection#'
+            path: 'system/src/Grav/Framework/Flex/FlexCollection.php'
+        -
+            message: '#Call to deprecated method (getAuthorizeScope|getActiveUser)\(\) of class Grav\\Framework\\Flex\\FlexObject#'
+            path: 'system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php'
         -
             message: '#deprecated class#'
             path: 'system/src/Grav/Framework/Uri/Uri.php'