In our case:

We want to redirect to payment gateway external URL in HTML form element tag through post action but its working fine as html file but when we add this HTML tags in Nintex form it does not work.

Below is the html form tag code snippet.

<form action="https://sbcheckout.payfort.com/FortAPI/paymentPage" method="post" name="frm">

<input type="hidden" name="access_code" value="ACCESSCODE">

<input type="hidden" name="currency" value="AED">

<input type="hidden" name="merchant_reference" value="MERCHANT">

<input type="hidden" name="amount" value="1000">

<input type="hidden" name="command" value="PURCHASE">

<input type="hidden" name="language" value="en">

<input type="hidden" name="order_description" value="Item">

<input type="hidden" name="merchant_identifier" value="IDENTIFIER">

<input type="hidden" name="customer_email" value="test@payfort.com">

<input type="hidden" name="signature" value="SIGNATURE">

<input type="submit" value="Click Me" class="green-btn" formtarget="_blank" id="submit2" name="SUBMIT2" alt="">

</form>