civicrm.org: registration failing for CiviCamp Birmingham

Reported on mattermost:

"Trying to register onto CiviCamp Birmingham and getting Invalid positive integer when I try to pay. Any ideas? " (@barijohn)

https://civicrm.org/civicrm/event/register?reset=1&id=1432

added civicrm.org label

Error message found in the logs:

Jan 09 18:35:16  [error]
$Fatal Error Details = array(3) {
  ["message"]=>
  string(49) "processor_id (value: ) is not of the type Integer"
[...]
      array(6) {
        ["file"]=> string(92) "/var/aegir/platforms/civicrm-d7/web/sites/all/modules/civicrm/CRM/Financial/Form/Payment.php"
        ["line"]=> int(53)
        ["function"]=> string(8) "retrieve"
        ["class"]=> string(17) "CRM_Utils_Request"
        ["type"]=> string(2) "::"
        ["args"]=> array(4) {
          [0]=> string(12) "processor_id"
          [1]=> string(7) "Integer"
          [2]=> &NULL
          [3]=> bool(true)
        }
      }

I think this is caused by Stripe and multiple participants - extensions/stripe#153 (closed)

You rock. Thank you for the lead.

I could reproduce that bug when registering two people in test mode:

I disable multi-reg for now.

Screenshot of the old config:

and I asked the CT if we can fund a fix.

Upgraded Stripe and re-opened multi-reg with the same profile config.

closed