Bundle Products not adding to the cart in magento1.9.1.0

Question

I am tackling with a strange problem in magento 1.9.1.0, the bundle products in my magento store are not being added to the cart instead when I click on the 'Add To Cart' button it's showing-

Error 503 Service Unavailable

  Service Unavailable Guru Meditation:

  XID: 2050290084

  Varnish cache server

All the other types of products are working fine and being added to cart normally.
There's a paypal checkout button on my product view page also which is also showing the same 503 error, so i checked the form but that just looks same as the others on simple or configurable products. When I used the same theme on localhost fresh installation it just worked fine and every product or even bundle product is being added to the cart.

I searched over internet regarding this error and implemented almost every way to resolve it, i disabled shopping cart rules, changed my bundle.xml with the default one, disabled other extensions, checked my view page but none of these helped.

I have also installed Mgt Commerce Varnish in my magento, may be that's generating the error. Hence I am not much familiar with the varnish, so I am not so sure about that.

So please somebody help me in resolving this issue.

Thanks

Answer 1

I solved this error finally. I just enabled the error_display and got this error:

Fatal error: Call to a member function getPosition() on a non-object in htdocs/app/code/core/Mage/Bundle/Model/Product/Type.php on line 850

So I tried to solve this error, I looked in the Type.php file and their I removed getOption() from the line 850 as:

From:

$a->getOption()->getPosition()

to:

$a->getPosition()

After this I got other errors in the same file, for them I did exactly the same and removed getOption() from all the error lines. And this worked!