Paypal - payment failed ob_get_contents

When I select paypal_standard payment at checkout, it doesnt go forward. The result will be an empty string. The output class variable is empty. I think there are something wrong around ob_get_contents at controller render method or is it a server specific bug?

when you say "Doesn't go forward" what are you referring to? Do you get sent to paypal? or just sits there?
There's nothing to check in the ob_get_contents... the issue is likely a javascript issue on the checkout page or something.
We need more details and a link to your site.

I select payment option radio button at payment at checkout and click to the continue button. I see two server request:

- index.php?route=checkout/payment server response: []
- index.php?route=checkout/confirm server response: {"output":null}

The checkout/confirm case the following happen:

The payment method is pp_standard and its template is: pp_standard.tpl
In the code: catalog/controller/checkout/confirm.php at the end of the file the $json['output'] = $this->render(); is NULL! because the controller's render method return null because the ob_get_contents() will be empty.

and the checkout process doesnt continue (no hidden paypal form generation)

Ok I found the problem.

The language file (pp_stanard.php) has some special characters. It is not coding in UTF8 and appear some question mark in it. I changed all and now it is ok. It creates the hidden form and after clicking confirm button it redirects to the paypal site!