php artisan not responding after upgrading laravel 5.1 to 5.2

php artisan not responding after upgrading laravel 5.1 to 5.2.

I followed the upgrade guide here http://ift.tt/1ZUwpUI

Even composer update gives an error at

Generating autoload files
> php artisan clear-compiled
Could not open input file: artisan
Script php artisan clear-compiled handling the post-update-cmd event returned with an error


  [RuntimeException]
  Error Output:

What might be the problem?

via Chebli Mohamed