CakePHP migration issue

I have a cakephp application that was working fine on my other AWS EC2 Ubuntu machine, after we moved the application to other AWS EC2 Ubuntu machine, the application loads but stop working. following is the error showing to me.

Shows "Error: An Internal Error Has Occurred".

Notice (8): Undefined variable: name [APP/View/Errors/error500.ctp, line 20]
Code Context

 */
?>
<h2><?php echo $name; ?></h2>

include - APP/View/Errors/error500.ctp, line 20
View::_evaluate() - CORE/Cake/View/View.php, line 945
View::_render() - CORE/Cake/View/View.php, line 907
View::render() - CORE/Cake/View/View.php, line 471
Controller::render() - CORE/Cake/Controller/Controller.php, line 948
AppExceptionRenderer::internalError() - APP/Lib/Error/AppExceptionRenderer.php, line 44
AppExceptionRenderer::missingConnection() - APP/Lib/Error/AppExceptionRenderer.php, line 92
ExceptionRenderer::render() - CORE/Cake/Error/ExceptionRenderer.php, line 178
ErrorHandler::handleException() - CORE/Cake/Error/ErrorHandler.php, line 123
[main] - [internal], line ??

Error: An Internal Error Has Occurred.
Fatal Error

Error: Call to a member function getTrace() on a non-object
File: /var/www/html/lib/Cake/View/Elements/exception_stack_trace.ctp
Line: 26

Notice: If you want to customize this error message, create app/View/Errors/fatal_error.ctp

below is my .htaccess file

<IfModule mod_rewrite.c>
   RewriteEngine on
   RewriteRule ^media/(.*) http://%{HTTP_HOST}/files/timthumb.php?src=http://%{HTTP_HOST}/app/webroot/files/$1 [L,R=301]
   RewriteRule    ^$ app/webroot/    [L]
   RewriteRule    (.*) app/webroot/$1 [L]
</IfModule>

how can I fix that?