Strange error every time saved in log file

[activestate10]

2013-09-03 13:30:27 Error: [MissingActionException] Action AppController::webroot() could not be found. Exception Attributes: array ( 'controller' => 'AppController', 'action' => 'webroot', ) Request URL: /cakecms/app/webroot/thumb/p7.png Stack Trace: #0 D:\XAMP\htdocs\cakecms\lib\Cake\Routing\Dispatcher.php(187): Controller->invokeAction(Object(CakeRequest)) #1 D:\XAMP\htdocs\cakecms\lib\Cake\Routing\Dispatcher.php(162): Dispatcher->_invoke(Object(AppController), Object(CakeRequest), Object(CakeResponse)) #2 D:\XAMP\htdocs\cakecms\app\webroot\index.php(110): Dispatcher->dispatch(Object(CakeRequest), Object(CakeResponse)) #3 {main}