- this probelm occurred when trying to upload files to the server in authenticated mode.:

1. Goto to Site Configuration > FCKeditor.
2. Under FCKEditor Settings. Select Advanced and click edit (under the Operations)

   - Under FKCEditor profile.
   - Expand File browser settings
   - Allow quick uploads: True
   - Path to uploaded files: %b%f/
   - Absolute path to uploaded files: %d%b%f/
   - Then click Update Profile to save settings

3. Proceed to the below path to edit config.php
   path: /drupal5test/modules/fckeditor/fckeditor/editor/filemanager/connectors/php/config.php

============= start of config file =============
global $Config ;

$Config['Enabled'] = true ;

$Config['UserFilesPath'] = '/sites/default/files/' ;

$Config['UserFilesAbsolutePath'] = '/<host root path to drupal platform>/sites/default/files/' ;

$Config['ForceSingleExtension'] = true ;

$Config['SecureImageUploads'] = true;
...
============= end of config file =============

         5. save the changes and retry uploading files again.