Aiax error on payment page with PayPal Web Payments Pro

Hi, I am having some strange happenings on a site using PayPal express checkout and PayPal Web Payments Pro.When you go through the checkout process on page 3 of 5 Payment page depending on the browser you get an ajax warning "An unknown response 'null null' was received while processing an ajax call. The action you requested could not be completed" It does not stop the process as you can continue. Can anyone throw any light on to why this is happening please?
Also on the checkout_payment page 4 of 5 I am seeing the order duplicated. Not too sure if this related.
Any guidance would be welcome, thanks.
By the way I have other sites running the same version on the server but using PayPal Standard or other gateway without any issues.

ianhg:

Hi, I am having some strange happenings on a site using PayPal express checkout and PayPal Web Payments Pro.When you go through the checkout process on page 3 of 5 Payment page depending on the browser you get an ajax warning "An unknown response 'null null' was received while processing an ajax call. The action you requested could not be completed" It does not stop the process as you can continue. Can anyone throw any light on to why this is happening please?
Also on the checkout_payment page 4 of 5 I am seeing the order duplicated. Not too sure if this related.
Any guidance would be welcome, thanks.
By the way I have other sites running the same version on the server but using PayPal Standard or other gateway without any issues.

Can you see where the Ajax is posting in your browser? what is the error it is giving? are you using any re-write modules?

Some additional information will help us help you (based on the information requested in the Posting Tips), specifically: Was this a fresh Zen Cart install? If not, what version was it upgraded from?

New install v 1.5.4
Using COWOA
As other sites have the same,, but are not getting Ajax error.
If you dismiss the error message you can complete purchase. Browser error just states
"An unknown response 'null null' was received while processing an ajax call. The action you requested could not be completed"

Which version of COWOA?

Did you merge or overwrite the template changes for COWOA?

If you switch to the "classic" theme (template) does this still occur?

Using COWOA 2.4
Overwrote template changes.

ianhg:

Using COWOA 2.4
Overwrote template changes.

Some further information if it helps:
in my template tpl_checkout_payment_default.php
I have the following in around line17 <div class="centerColumn" id="checkoutPayment">

<?php echo zen_draw_form('checkout_payment', zen_href_link(FILENAME_CHECKOUT_CONFIRMATION, '', 'SSL'), 'post', ($flagOnSubmit ? 'onsubmit="return check_form();"' : '')); ?>

In the non modified template the red highlighted section is missing.
On around line 230 in my modified template I have <div class="buttonRow forward"><?php echo zen_image_submit(BUTTON_IMAGE_CONTINUE_CHECKOUT, BUTTON_CONTINUE_ALT, 'onclick="submitFunction('.zen_user_has_gv_account($_SESSION['customer_id']).','.$order->info['total'].')"'); ?></div>

<div class="buttonRow forward"><?php echo TITLE_CONTINUE_CHECKOUT_PROCEDURE . '<br />' . TEXT_CONTINUE_CHECKOUT_PROCEDURE; ?></div> But in the zen standard template: <div class="buttonRow forward" id="paymentSubmit"><?php echo zen_image_submit(BUTTON_IMAGE_CONTINUE_CHECKOUT, BUTTON_CONTINUE_ALT, 'onclick="submitFunction('.zen_user_has_gv_account($_SESSION['customer_id']).','.$order->info['total'].')"'); ?></div> <div class="buttonRow back"><?php echo TITLE_CONTINUE_CHECKOUT_PROCEDURE . '<br />' . TEXT_CONTINUE_CHECKOUT_PROCEDURE; ?></div> So I am missing the red highlighted section. Would this be the cause of the error message from Ajax? So should I add to my template id="paymentSubmit"

There was another posting (by @earth-friendly) of the same error which was corrected by properly merging the template files for the checkout_payment page.

I'm pretty sure that the correction was, as you suggested, adding that id="paymentSubmit" to the div that surrounds the page's submit button.

lat9:

There was another posting (by @earth-friendly) of the same error which was corrected by properly merging the template files for the checkout_payment page.

I'm pretty sure that the correction was, as you suggested, adding that id="paymentSubmit" to the div that surrounds the page's submit button.

Thanks for the reply but I not too sure if I should also remove

, ($flagOnSubmit ? 'onsubmit="return check_form();"' : '')

As this is not in Zencart 1.5.4 template

ianhg:

Thanks for the reply but I not too sure if I should also remove

, ($flagOnSubmit ? 'onsubmit="return check_form();"' : '')

As this is not in Zencart 1.5.4 template
Apologies for providing an incomplete solution in my previous post; yes, I would also remove that code fragment.

lat9:

Apologies for providing an incomplete solution in my previous post; yes, I would also remove that code fragment.

Thanks I did that on my test site and it solved the problem.
Appreciate the help. So if anyone else is running zencart 1.5.4 with this version of COWOA there maybe a need to modify the template.