diff --git a/CHANGELOG.md b/CHANGELOG.md
index 323774a0c..ee5fd1cb9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -4,39 +4,40 @@
 1. [](#new)
     * Added `select()` and `unselect()` methods to `CollectionInterface` and its base classes
     * Added `orderBy()` and `limit()` methods to `ObjectCollectionInterface` and its base classes
-    * Flex: Added support for custom object index classes (API compatibility break)
     * Added `user-data://` which is a writable stream (`user://data` is not and should be avoided)
     * Added support for `/action:{$action}` (like task but used without nonce when only receiving data)
     * Added `onAction.{$action}` event
     * Added `Grav\Framework\Form\FormFlash` class to contain AJAX uploaded files in more reliable way
     * Added `Grav\Framework\Form\FormFlashFile` class which implements `UploadedFileInterface` from PSR-7
     * Added `Grav\Framework\Filesystem\Filesystem` class with methods to manipulate stream URLs
+    * Grav 1.6: Flex: Added support for custom object index classes (API compatibility break)
 1. [](#improved)
-    * Improved Flex storage classes
     * Improved `Grav\Framework\File\Formatter` classes to have abstract parent class and some useful methods
+    * Grav 1.6: Improved Flex storage classes
+    * Grav 1.6: Improved `Grav\Framework\File` classes to use better type hints and the new `Filesystem` class
 1. [](#bugfix)
     * Fixed handling of `append_url_extension` inside of `Page::templateFormat()` [#2264](https://github.com/getgrav/grav/issues/2264) 
     * Fixed a broken language string [#2261](https://github.com/getgrav/grav/issues/2261)
     * Fixed clearing cache having no effect on Doctrine cache
     * Fixed `Medium::relativePath()` for streams
-    * Fixed `FlexObject::update()` call with partial object update
     * Fixed `Object` serialization breaking if overriding `jsonSerialize()` method
+    * Grav 1.6: Fixed `FlexObject::update()` call with partial object update
 
 # v1.6.0-beta.6
 ## 11/12/2018
 
 1. [](#new)
-    * Added `CsvFormatter` and `CsvFile` classes
     * Added `$grav->setup()` to simplify CLI and custom access points
+    * Grav 1.6: Added `CsvFormatter` and `CsvFile` classes
 1. [](#improved)
     * Support negotiated content types set via the Request `Accept:` header
     * Support negotiated language types set via the Request `Accept-Language:` header
-    * Allow custom Flex form views
     * Cleaned up and sorted the Service `idMap`
+    * Grav 1.6: Allow custom Flex form views
 1. [](#bugfix)
     * Fixed `Uri::hasStandardPort()` to support reverse proxy configurations [#1786](https://github.com/getgrav/grav/issues/1786)
     * Use `append_url_extension` from page header to set template format if set [#2604](https://github.com/getgrav/grav/pull/2064)
-    * Fixed some bugs in environment selection
+    * Fixed some bugs in Grav environment selection logic
 
 # v1.6.0-beta.5
 ## 11/05/2018
@@ -55,7 +56,7 @@
     * Set session name based on `security.salt` rather than `GRAV_ROOT` [#2242](https://github.com/getgrav/grav/issues/2242)
     * Added option to configure list of `xss_invalid_protocols` in `Security` config [#2250](https://github.com/getgrav/grav/issues/2250)
     * Smarter `security.salt` checking now we use `security.yaml` for other options
-    * Merged Grav 1.5.4 fixes in
+    * Grav 1.6: Merged Grav 1.5.4 fixes in
 
 # v1.6.0-beta.4
 ## 10/24/2018
@@ -84,15 +85,15 @@
 ## 10/09/2018
 
 1. [](#new)
-    * Added Flex support for custom media tasks
+    * Grav 1.6: Added Flex support for custom media tasks
 1. [](#improved)
     * Added support for syslog and syslog facility logging (default: 'file')
     * Improved usability of `System` configuration blueprint with side-tabs
 1. [](#bugfix)
     * Fixed asset manager to not add empty assets when they don't exist in the filesystem
-    * Regression: Fixed asset manager methods with default legacy attributes
     * Update `script` and `style` Twig tags to use the new `Assets` classes
     * Fixed asset pipeline to rewrite remote URLs as well as local [#2216](https://github.com/getgrav/grav/issues/2216)
+    * Grav 1.6: Regression: Fixed asset manager methods with default legacy attributes
 
 # v1.6.0-beta.1
 ## 10/01/2018
diff --git a/system/src/Grav/Framework/File/AbstractFile.php b/system/src/Grav/Framework/File/AbstractFile.php
index 0023d48ce..9317a6949 100644
--- a/system/src/Grav/Framework/File/AbstractFile.php
+++ b/system/src/Grav/Framework/File/AbstractFile.php
@@ -12,9 +12,13 @@ declare(strict_types=1);
 namespace Grav\Framework\File;
 
 use Grav\Framework\File\Interfaces\FileInterface;
+use Grav\Framework\Filesystem\Filesystem;
 
 class AbstractFile implements FileInterface
 {
+    /** @var Filesystem */
+    private $filesystem;
+
     /** @var string */
     private $filepath;
 
@@ -36,8 +40,13 @@ class AbstractFile implements FileInterface
     /** @var bool */
     private $locked = false;
 
-    public function __construct($filepath)
+    /**
+     * @param string $filepath
+     * @param Filesystem|null $filesystem
+     */
+    public function __construct(string $filepath, Filesystem $filesystem = null)
     {
+        $this->filesystem = $filesystem ?? new Filesystem();
         $this->setFilepath($filepath);
     }
 
@@ -51,11 +60,26 @@ class AbstractFile implements FileInterface
         }
     }
 
-    /**
-     * Prevent cloning.
-     */
-    private function __clone()
+    public function __clone()
     {
+        $this->handle = null;
+        $this->locked = false;
+    }
+
+    /**
+     * @return string
+     */
+    public function serialize(): string
+    {
+        return serialize($this->doSerialize());
+    }
+
+    /**
+     * @param string $serialized
+     */
+    public function unserialize($serialized): void
+    {
+        $this->doUnserialize(unserialize($serialized, ['allowed_classes' => false]));
     }
 
     /**
@@ -63,7 +87,7 @@ class AbstractFile implements FileInterface
      *
      * @return string
      */
-    public function getFilePath() : string
+    public function getFilePath(): string
     {
         return $this->filepath;
     }
@@ -73,7 +97,7 @@ class AbstractFile implements FileInterface
      *
      * @return string
      */
-    public function getPath() : string
+    public function getPath(): string
     {
         if (null === $this->path) {
             $this->setPathInfo();
@@ -87,7 +111,7 @@ class AbstractFile implements FileInterface
      *
      * @return string
      */
-    public function getFilename() : string
+    public function getFilename(): string
     {
         if (null === $this->filename) {
             $this->setPathInfo();
@@ -101,7 +125,7 @@ class AbstractFile implements FileInterface
      *
      * @return string
      */
-    public function getBasename() : string
+    public function getBasename(): string
     {
         if (null === $this->basename) {
             $this->setPathInfo();
@@ -113,10 +137,10 @@ class AbstractFile implements FileInterface
     /**
      * Return file extension.
      *
-     * @param $withDot
+     * @param bool $withDot
      * @return string
      */
-    public function getExtension($withDot = false) : string
+    public function getExtension(bool $withDot = false): string
     {
         if (null === $this->extension) {
             $this->setPathInfo();
@@ -130,7 +154,7 @@ class AbstractFile implements FileInterface
      *
      * @return bool
      */
-    public function exists() : bool
+    public function exists(): bool
     {
         return is_file($this->filepath);
     }
@@ -138,21 +162,21 @@ class AbstractFile implements FileInterface
     /**
      * Return file modification time.
      *
-     * @return int|bool Timestamp or false if file doesn't exist.
+     * @return int Unix timestamp. If file does not exist, method returns current time.
      */
-    public function getCreationTime()
+    public function getCreationTime(): int
     {
-        return is_file($this->filepath) ? filectime($this->filepath) : false;
+        return is_file($this->filepath) ? filectime($this->filepath) : time();
     }
 
     /**
      * Return file modification time.
      *
-     * @return int|bool Timestamp or false if file doesn't exist.
+     * @return int Unix timestamp. If file does not exist, method returns current time.
      */
-    public function getModificationTime()
+    public function getModificationTime(): int
     {
-        return is_file($this->filepath) ? filemtime($this->filepath) : false;
+        return is_file($this->filepath) ? filemtime($this->filepath) : time();
     }
 
     /**
@@ -162,7 +186,7 @@ class AbstractFile implements FileInterface
      * @return bool
      * @throws \RuntimeException
      */
-    public function lock($block = true) : bool
+    public function lock(bool $block = true): bool
     {
         if (!$this->handle) {
             if (!$this->mkdir($this->getPath())) {
@@ -184,7 +208,7 @@ class AbstractFile implements FileInterface
      *
      * @return bool
      */
-    public function unlock() : bool
+    public function unlock(): bool
     {
         if (!$this->handle) {
             return false;
@@ -204,25 +228,39 @@ class AbstractFile implements FileInterface
      *
      * @return bool True = locked, false = not locked.
      */
-    public function isLocked() : bool
+    public function isLocked(): bool
     {
         return $this->locked;
     }
 
+    /**
+     * Check if file exists and can be read.
+     *
+     * @return bool
+     */
+    public function isReadable(): bool
+    {
+        return is_readable($this->filepath) && is_file($this->filepath);
+    }
+
     /**
      * Check if file can be written.
      *
      * @return bool
      */
-    public function isWritable() : bool
+    public function isWritable(): bool
     {
-        return is_writable($this->filepath) || $this->isWritableDir($this->getPath());
+        if (!file_exists($this->filepath)) {
+            return $this->isWritablePath($this->getPath());
+        }
+
+        return is_writable($this->filepath) && is_file($this->filepath);
     }
 
     /**
-     * (Re)Load a file and return RAW file contents.
+     * (Re)Load a file and return file contents.
      *
-     * @return string
+     * @return string|array|false
      */
     public function load()
     {
@@ -235,7 +273,7 @@ class AbstractFile implements FileInterface
      * @param  mixed $data
      * @throws \RuntimeException
      */
-    public function save($data)
+    public function save($data): void
     {
         $lock = false;
         if (!$this->locked) {
@@ -266,7 +304,7 @@ class AbstractFile implements FileInterface
      * @param string $path
      * @return bool
      */
-    public function rename($path) : bool
+    public function rename(string $path): bool
     {
         if ($this->exists() && !@rename($this->filepath, $path)) {
             return false;
@@ -282,7 +320,7 @@ class AbstractFile implements FileInterface
      *
      * @return bool
      */
-    public function delete() : bool
+    public function delete(): bool
     {
         return @unlink($this->filepath);
     }
@@ -293,7 +331,7 @@ class AbstractFile implements FileInterface
      * @throws \RuntimeException
      * @internal
      */
-    protected function mkdir($dir) : bool
+    protected function mkdir(string $dir): bool
     {
         // Silence error for open_basedir; should fail in mkdir instead.
         if (!@is_dir($dir)) {
@@ -310,20 +348,27 @@ class AbstractFile implements FileInterface
     }
 
     /**
-     * @param  string  $dir
-     * @return bool
-     * @internal
+     * @return array
      */
-    protected function isWritableDir($dir) : bool
+    protected function doSerialize(): array
     {
-        if ($dir && !file_exists($dir)) {
-            return $this->isWritableDir(\dirname($dir));
-        }
-
-        return $dir && is_dir($dir) && is_writable($dir);
+        return [
+            'filepath' => $this->filepath
+        ];
     }
 
-    protected function setFilepath($filepath) : void
+    /**
+     * @param array $serialized
+     */
+    protected function doUnserialize(array $serialized): void
+    {
+        $this->setFilepath($serialized['filepath']);
+    }
+
+    /**
+     * @param string $filepath
+     */
+    protected function setFilepath(string $filepath): void
     {
         $this->filepath = $filepath;
         $this->filename = null;
@@ -332,64 +377,32 @@ class AbstractFile implements FileInterface
         $this->extension = null;
     }
 
-    protected function setPathInfo() : void
+    protected function setPathInfo(): void
     {
-        $pathInfo = static::pathinfo($this->filepath);
-        $this->filename = $pathInfo['filename'];
-        $this->basename = $pathInfo['basename'];
-        $this->path = $pathInfo['dirname'];
-        $this->extension = $pathInfo['extension'];
+        $pathInfo = $this->filesystem->pathinfo($this->filepath);
+
+        $this->filename = $pathInfo['filename'] ?? null;
+        $this->basename = $pathInfo['basename'] ?? null;
+        $this->path = $pathInfo['dirname'] ?? null;
+        $this->extension = $pathInfo['extension'] ?? null;
     }
 
     /**
-     * Multi-byte-safe pathinfo replacement.
-     * Replacement for pathinfo(), but stream, multibyte and cross-platform safe.
-     *
-     * @see    http://www.php.net/manual/en/function.pathinfo.php
-     *
-     * @param string     $path    A filename or path, does not need to exist as a file
-     * @param int|string $options Either a PATHINFO_* constant,
-     *                            or a string name to return only the specified piece
-     *
-     * @return string|array
+     * @param  string  $dir
+     * @return bool
+     * @internal
      */
-    public static function pathinfo($path, $options = null)
+    protected function isWritablePath(string $dir): bool
     {
-        $ret = ['scheme' => '', 'dirname' => '', 'basename' => '', 'extension' => '', 'filename' => ''];
-        $pathinfo = [];
-        if (preg_match('#^((.*?)://)?(.*?)[\\\\/]*(([^/\\\\]*?)(\.([^\.\\\\/]+?)|))[\\\\/\.]*$#um', $path, $pathinfo)) {
-            if (array_key_exists(1, $pathinfo)) {
-                $ret['scheme'] = $pathinfo[2];
-                $ret['dirname'] = $pathinfo[1];
-            }
-            if (array_key_exists(3, $pathinfo)) {
-                $ret['dirname'] .= $pathinfo[3];
-            }
-            if (array_key_exists(4, $pathinfo)) {
-                $ret['basename'] = $pathinfo[4];
-            }
-            if (array_key_exists(7, $pathinfo)) {
-                $ret['extension'] = $pathinfo[7];
-            }
-            if (array_key_exists(5, $pathinfo)) {
-                $ret['filename'] = $pathinfo[5];
-            }
+        if ($dir === '') {
+            return false;
         }
-        switch ($options) {
-            case PATHINFO_DIRNAME:
-            case 'dirname':
-                return $ret['dirname'];
-            case PATHINFO_BASENAME:
-            case 'basename':
-                return $ret['basename'];
-            case PATHINFO_EXTENSION:
-            case 'extension':
-                return $ret['extension'];
-            case PATHINFO_FILENAME:
-            case 'filename':
-                return $ret['filename'];
-            default:
-                return $ret;
+
+        if (!file_exists($dir)) {
+            // Recursively look up in the directory tree.
+            return $this->isWritablePath($this->filesystem->parent($dir));
         }
+
+        return is_dir($dir) && is_writable($dir);
     }
 }
diff --git a/system/src/Grav/Framework/File/DataFile.php b/system/src/Grav/Framework/File/DataFile.php
index fd6b8957f..cd8fe1c89 100644
--- a/system/src/Grav/Framework/File/DataFile.php
+++ b/system/src/Grav/Framework/File/DataFile.php
@@ -34,7 +34,7 @@ class DataFile extends AbstractFile
     /**
      * (Re)Load a file and return RAW file contents.
      *
-     * @return array
+     * @return array|false
      * @throws RuntimeException
      */
     public function load()
@@ -42,7 +42,7 @@ class DataFile extends AbstractFile
         $raw = parent::load();
 
         try {
-            return $this->formatter->decode($raw);
+            return $raw !== false ? $this->formatter->decode($raw) : false;
         } catch (RuntimeException $e) {
             throw new RuntimeException(sprintf("Failed to load file '%s': %s", $this->getFilePath(), $e->getMessage()), $e->getCode(), $e);
         }
@@ -54,9 +54,10 @@ class DataFile extends AbstractFile
      * @param  string|array  $data  Data to be saved.
      * @throws RuntimeException
      */
-    public function save($data)
+    public function save($data): void
     {
         if (\is_string($data)) {
+            // Make sure that the string is valid data.
             try {
                 $this->formatter->decode($data);
             } catch (RuntimeException $e) {
diff --git a/system/src/Grav/Framework/File/File.php b/system/src/Grav/Framework/File/File.php
index bcac43941..31072b43c 100644
--- a/system/src/Grav/Framework/File/File.php
+++ b/system/src/Grav/Framework/File/File.php
@@ -16,11 +16,11 @@ class File extends AbstractFile
     /**
      * Load a file from the filesystem.
      *
-     * @return string
+     * @return string|false
      */
     public function load()
     {
-        return (string) parent::load();
+        return parent::load();
     }
 
     /**
@@ -29,8 +29,12 @@ class File extends AbstractFile
      * @param  string $data
      * @throws \RuntimeException
      */
-    public function save($data)
+    public function save($data): void
     {
+        if (!\is_string($data)) {
+            throw new \RuntimeException('Cannot save data, string required');
+        }
+
         parent::save($data);
     }
 }
diff --git a/system/src/Grav/Framework/File/Interfaces/FileInterface.php b/system/src/Grav/Framework/File/Interfaces/FileInterface.php
index 3aa8745ea..9c727398b 100644
--- a/system/src/Grav/Framework/File/Interfaces/FileInterface.php
+++ b/system/src/Grav/Framework/File/Interfaces/FileInterface.php
@@ -11,64 +11,64 @@ declare(strict_types=1);
 
 namespace Grav\Framework\File\Interfaces;
 
-interface FileInterface
+interface FileInterface extends \Serializable
 {
     /**
      * Get full path to the file.
      *
      * @return string
      */
-    public function getFilePath() : string;
+    public function getFilePath(): string;
 
     /**
      * Get path to the file.
      *
      * @return string
      */
-    public function getPath() : string;
+    public function getPath(): string;
 
     /**
      * Get filename.
      *
      * @return string
      */
-    public function getFilename() : string;
+    public function getFilename(): string;
 
     /**
      * Return name of the file without extension.
      *
      * @return string
      */
-    public function getBasename() : string;
+    public function getBasename(): string;
 
     /**
      * Return file extension.
      *
-     * @param $withDot
+     * @param bool $withDot
      * @return string
      */
-    public function getExtension($withDot = false) : string;
+    public function getExtension(bool $withDot = false): string;
 
     /**
      * Check if file exits.
      *
      * @return bool
      */
-    public function exists() : bool;
+    public function exists(): bool;
 
     /**
      * Return file modification time.
      *
-     * @return int|bool Timestamp or false if file doesn't exist.
+     * @return int Unix timestamp. If file does not exist, method returns current time.
      */
-    public function getCreationTime();
+    public function getCreationTime(): int;
 
     /**
      * Return file modification time.
      *
-     * @return int|bool Timestamp or false if file doesn't exist.
+     * @return int Unix timestamp. If file does not exist, method returns current time.
      */
-    public function getModificationTime();
+    public function getModificationTime(): int;
 
     /**
      * Lock file for writing. You need to manually unlock().
@@ -77,33 +77,40 @@ interface FileInterface
      * @return bool
      * @throws \RuntimeException
      */
-    public function lock($block = true) : bool;
+    public function lock(bool $block = true): bool;
 
     /**
      * Unlock file.
      *
      * @return bool
      */
-    public function unlock() : bool;
+    public function unlock(): bool;
 
     /**
      * Returns true if file has been locked for writing.
      *
      * @return bool True = locked, false = not locked.
      */
-    public function isLocked() : bool;
+    public function isLocked(): bool;
+
+    /**
+     * Check if file exists and can be read.
+     *
+     * @return bool
+     */
+    public function isReadable(): bool;
 
     /**
      * Check if file can be written.
      *
      * @return bool
      */
-    public function isWritable() : bool;
+    public function isWritable(): bool;
 
     /**
      * (Re)Load a file and return RAW file contents.
      *
-     * @return string
+     * @return string|array|false
      */
     public function load();
 
@@ -113,7 +120,7 @@ interface FileInterface
      * @param  mixed $data
      * @throws \RuntimeException
      */
-    public function save($data);
+    public function save($data): void;
 
     /**
      * Rename file in the filesystem if it exists.
@@ -121,26 +128,12 @@ interface FileInterface
      * @param string $path
      * @return bool
      */
-    public function rename($path) : bool;
+    public function rename(string $path): bool;
 
     /**
      * Delete file from filesystem.
      *
      * @return bool
      */
-    public function delete() : bool;
-
-    /**
-     * Multi-byte-safe pathinfo replacement.
-     * Replacement for pathinfo(), but stream, multibyte and cross-platform safe.
-     *
-     * @see    http://www.php.net/manual/en/function.pathinfo.php
-     *
-     * @param string     $path    A filename or path, does not need to exist as a file
-     * @param int|string $options Either a PATHINFO_* constant,
-     *                            or a string name to return only the specified piece
-     *
-     * @return string|array
-     */
-    public static function pathinfo($path, $options = null);
+    public function delete(): bool;
 }