While checkout in Magento, after providing checkout method, Billing information, Shipping information,Shipping method, Payment information
the site is redirecting to cart page.
That is in Payment information section we can select the payment gateway (here either paytm or ccavenue), after selecting any payment gateway option the site is redirect to cart page instead of payment page.
EDIT
When I click continue button after selecting the payment gate way(paytm or ccavenue) I got error in console:
...checkout/onepage/savePayment/ 500 Internal Server Error