diff --git a/system/src/Grav/Framework/Flex/FlexIndex.php b/system/src/Grav/Framework/Flex/FlexIndex.php
index 0b5470a53..c716472a9 100644
--- a/system/src/Grav/Framework/Flex/FlexIndex.php
+++ b/system/src/Grav/Framework/Flex/FlexIndex.php
@@ -332,7 +332,7 @@ class FlexIndex extends ObjectIndex implements FlexCollectionInterface, FlexInde
      * @param string $key
      * @return array
      */
-    public function getMetaData(string $key): array
+    public function getMetaData($key): array
     {
         return $this->getEntries()[$key] ?? [];
     }
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php
index 5fd835abe..b775edb4f 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageAuthorsTrait.php
@@ -240,8 +240,4 @@ trait PageAuthorsTrait
 
         return $list;
     }
-
-    abstract public function getNestedProperty($property, $default = null, $separator = null);
-
-    abstract protected function loadAccounts();
 }
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageContentTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageContentTrait.php
index b0ad03e48..fb95f35d9 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageContentTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageContentTrait.php
@@ -500,15 +500,9 @@ trait PageContentTrait
     }
 
     /**
-     * @inheritdoc
+     * @param Header|stdClass|array|null $value
+     * @return Header
      */
-    abstract public function exists(): bool;
-
-    abstract public function getProperty($property, $default = null);
-    abstract public function setProperty($property, $value);
-    abstract public function &getArrayProperty($property, $default = null, $doCreate = false);
-
-
     protected function offsetLoad_header($value)
     {
         if ($value instanceof Header) {
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php
index 32b590e88..042deefac 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageLegacyTrait.php
@@ -1107,33 +1107,4 @@ trait PageLegacyTrait
 
         return null;
     }
-
-    /**
-     * @param string|null $namespace
-     * @return CacheInterface
-     */
-    abstract public function getCache(string $namespace = null);
-
-    /**
-     * @param PageInterface|null $var
-     * @return PageInterface|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 2b3301ed2..5d5b25428 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageRoutableTrait.php
@@ -545,6 +545,4 @@ trait PageRoutableTrait
 
         return $this->root === true || $this->getKey() === '/';
     }
-
-    abstract protected function loadHeaderProperty(string $property, $var, callable $filter);
 }
diff --git a/system/src/Grav/Framework/Flex/Pages/Traits/PageTranslateTrait.php b/system/src/Grav/Framework/Flex/Pages/Traits/PageTranslateTrait.php
index dcb0db98e..a1aa05410 100644
--- a/system/src/Grav/Framework/Flex/Pages/Traits/PageTranslateTrait.php
+++ b/system/src/Grav/Framework/Flex/Pages/Traits/PageTranslateTrait.php
@@ -280,6 +280,4 @@ trait PageTranslateTrait
 
         return $fallback ? $language->getFallbackLanguages($languageCode, true) : [$languageCode];
     }
-
-    abstract protected function loadHeaderProperty(string $property, $var, callable $filter);
 }
diff --git a/system/src/Grav/Framework/Flex/Storage/SimpleStorage.php b/system/src/Grav/Framework/Flex/Storage/SimpleStorage.php
index bab57414c..a3de076b1 100644
--- a/system/src/Grav/Framework/Flex/Storage/SimpleStorage.php
+++ b/system/src/Grav/Framework/Flex/Storage/SimpleStorage.php
@@ -31,10 +31,10 @@ class SimpleStorage extends AbstractFilesystemStorage
     protected $dataPattern;
     /** @var string */
     protected $prefix;
-    /** @var array */
+    /** @var array|null */
     protected $data;
     /** @var int */
-    protected $modified;
+    protected $modified = 0;
 
     /**
      * {@inheritdoc}
@@ -76,7 +76,7 @@ class SimpleStorage extends AbstractFilesystemStorage
     public function clearCache(): void
     {
         $this->data = null;
-        $this->modified = null;
+        $this->modified = 0;
     }
 
     /**
diff --git a/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php b/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php
index 7aaa6d6af..9a8048529 100644
--- a/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php
+++ b/system/src/Grav/Framework/Flex/Traits/FlexMediaTrait.php
@@ -117,6 +117,10 @@ trait FlexMediaTrait
     public function checkUploadedMediaFile(UploadedFileInterface $uploadedFile, string $filename = null, string $field = null)
     {
         $media = $this->getMedia();
+        if (!$media instanceof MediaUploadInterface) {
+            throw new RuntimeException("Media for {$this->getFlexDirectory()->getFlexType()} doesn't support file uploads.");
+        }
+
         $media->checkUploadedFile($uploadedFile, $filename, $this->getMediaFieldSettings($field ?? ''));
     }
 
@@ -130,8 +134,12 @@ trait FlexMediaTrait
     public function uploadMediaFile(UploadedFileInterface $uploadedFile, string $filename = null, string $field = null): void
     {
         $media = $this->getMedia();
+        if (!$media instanceof MediaUploadInterface) {
+            throw new RuntimeException("Media for {$this->getFlexDirectory()->getFlexType()} doesn't support file uploads.");
+        }
+
         $settings = $this->getMediaFieldSettings($field ?? '');
-        $media->checkUploadedFile($uploadedFile, $filename, $settings);
+        $filename = $media->checkUploadedFile($uploadedFile, $filename, $settings);
         $media->copyUploadedFile($uploadedFile, $filename, $settings);
         $this->clearMediaCache();
     }
@@ -144,6 +152,10 @@ trait FlexMediaTrait
     public function deleteMediaFile(string $filename): void
     {
         $media = $this->getMedia();
+        if (!$media instanceof MediaUploadInterface) {
+            throw new RuntimeException("Media for {$this->getFlexDirectory()->getFlexType()} doesn't support file uploads.");
+        }
+
         $media->deleteFile($filename);
         $this->clearMediaCache();
     }
@@ -165,6 +177,10 @@ trait FlexMediaTrait
     protected function setUpdatedMedia(array $files): void
     {
         $media = $this->getMedia();
+        if (!$media instanceof MediaUploadInterface) {
+            return;
+        }
+
         $filesystem = Filesystem::getInstance(false);
 
         $list = [];
@@ -263,6 +279,10 @@ trait FlexMediaTrait
     protected function saveUpdatedMedia(): void
     {
         $media = $this->getMedia();
+        if (!$media instanceof MediaUploadInterface) {
+            return;
+        }
+
 
         // Upload/delete altered files.
         /**
diff --git a/system/src/Grav/Framework/Flex/Traits/FlexRelatedDirectoryTrait.php b/system/src/Grav/Framework/Flex/Traits/FlexRelatedDirectoryTrait.php
index 59e65e559..0adfff75b 100644
--- a/system/src/Grav/Framework/Flex/Traits/FlexRelatedDirectoryTrait.php
+++ b/system/src/Grav/Framework/Flex/Traits/FlexRelatedDirectoryTrait.php
@@ -56,6 +56,4 @@ trait FlexRelatedDirectoryTrait
 
         return $directory;
     }
-
-    abstract public function getNestedProperty($property, $default = null, $separator = null);
 }