php 5.4+ missing payment type in $_SESSION on checkout_process

[DrByte]

Unit tests go a long way to preventing bugs and proving that things work not just on the dev's box.

Agreed entirely. But, someone has to write them. And as you know, procedural code doesn't lend itself well to unit tests.
And that's a discussion we've already had in other forum channels.
That said, thanks for your recent PR's for v1.6.0.

[DrByte]

$_SESSION['payment'] is only reset during processing if $credit_covers is true, and that happens only when the order-total modules determine that any discounts (coupons, gift certificates, etc) equal or exceed the total purchase price, thus determining that there is no payment required. And in that case the store expects that you also have the freecharger module enabled so that it can catch that 0.00 price scenario and complete checkout without requiring payment.

I see from your var_dump that you have $_SESSION['cc_id'] set, which indicates that the system attempted to process a coupon.
And, you stated later that you don't have freecharger enabled.

Does enabling freecharger help?

[texdc]

I've been swamped @ work and added a hack to keep things working until I could dig deeper into this. Here's my solution: `session_write_close()` should be called at the end of every page/script. `zen_session_close()` needs to be fixed:

function zen_session_close() {
  session_write_close();
}