Error: Uncaught Exception: Cannot move .../assets/image-gallery/Images-2/ to .../assets/image-gallery/Images-2/
At line 422 in .../sapphire/filesystem/File.php

   public function updateFilesystem() {
      // Regenerate "Filename", just to be sure
      $this->setField('Filename', $this->getRelativePath());
      
      // If certain elements are changed, update the filesystem reference
      if(!$this->isChanged('Filename')) return false;
      
      $changedFields = $this->getChangedFields();
      $pathBefore = $changedFields['Filename']['before'];
      $pathAfter = $changedFields['Filename']['after'];
      
      // If the file or folder didn't exist before, don't rename - its created
      if(!$pathBefore) return;
      
      $pathBeforeAbs = Director::getAbsFile($pathBefore);
      $pathAfterAbs = Director::getAbsFile($pathAfter);
      
      // TODO Fix Filetest->testCreateWithFilenameWithSubfolder() to enable this
      // // Create parent folders recursively in database and filesystem
      // if(!is_a($this, 'Folder')) {
      //    $folder = Folder::findOrMake(dirname($pathAfterAbs));
      //    if($folder) $this->ParentID = $folder->ID;
      // }
      
      // Check that original file or folder exists, and rename on filesystem if required.
      // The folder of the path might've already been renamed by Folder->updateFilesystem()
      // before any filesystem update on contained file or subfolder records is triggered.
      if(!file_exists($pathAfterAbs)) {
         if(!is_a($this, 'Folder')) {
            // Only throw a fatal error if *both* before and after paths don't exist.
            if(!file_exists($pathBeforeAbs)) throw new Exception("Cannot move $pathBefore to $pathAfter - $pathBefore doesn't exist");
            
            // Check that target directory (not the file itself) exists.
            // Only check if we're dealing with a file, otherwise the folder will need to be created
            if(!file_exists(dirname($pathAfterAbs))) throw new Exception("Cannot move $pathBefore to $pathAfter - Directory " . dirname($pathAfter) . " doesn't exist");
         }
         
         // Rename file or folder
         $success = rename($pathBeforeAbs, $pathAfterAbs);
         if(!$success) throw new Exception("Cannot move $pathBeforeAbs to $pathAfterAbs"); //Line 422
      }
      
      
      // Update any database references
      $this->updateLinks($pathBefore, $pathAfter);
   }

[Notice] Trying to get property of non-object
POST /admin/EditForm/field/GalleryItems/UploadifyForm?SecurityID=7dcd5a408c673ebde9afccff1276a527c2076180&ctf[GalleryItems][start]=0&ctf[GalleryItems][per_page]=10&ctf[GalleryItems][showall]=0&ctf[GalleryItems][sort]=SortOrder&ctf[GalleryItems][sort_dir]=&ctf[GalleryItems][search]=&ctf[GalleryItems][filter]=AlbumID_2&ctf[GalleryItems][view]=grid&ctf[GalleryItems][imagesize]=100

Line 418 in /Applications/MAMP/htdocs/silverstripe/nttanks/dataobject_manager/code/FileDataObjectManager.php