file_put_content...fail to open stream:Permission denied in Laravel 5

is a file permissions issue as lesssugar said , you need to give writte permissions to the storage folder , so go to your html/Tranining-management-system.. folder an then you can do :

chmod -R 0777 storage/

That will change to writte access Recursively .

Please read the configuration section in docs :

http://laravel.com/docs/master#configuration

You have to do the same with the cache folder.

I run php artisan view:cache and it solved the issue