There are different reasons for this Error. One of the most common reason is using Htaccess.
This error is most common while using htaccess. If htaccess is not enable in localhost we will get this error.
We can solve this error by enable the Htaccess
Open AppSer installed folder in that find conf folder and find httpd.conf file. In that file find below line(LoadModule rewrite_module modules/mod_rewrite.so)
For Example In Windows: D:/AppServ/Apache2.2/conf
"LoadModule rewrite_module modules/mod_rewrite.so"
If hash is there before the line remove that hash(“#”) and save the file and restart the AppServer to work
You can debug this by enabling the errors by doing this:
In your php file:
ini_set('display_errors', 1);
In .htaccess file:
php_flag display_errors 1