Here is the fix.
If you turn on WP_DEBUG ( see https://codex.www.ads-software.com/WP_DEBUG ) you will see amid the numerous warnings, due to sloppy coding, an actual WordPress database error, before the page forwards due to meta refresh html tag after 3 seconds. The column cannot by NULL.
In our case it was event-registration/payments/evr_admin_payments-post.php
but event-registration/payments/evr_admin_payments-update.php
has the same code.
A fix is to search and replace in those two files:
search: $_REQUEST
replace: (string)@$_REQUEST
Except in these two places:
1.
delete: (is_numeric($_REQUEST['event_id'])) ? $event_id = $_REQUEST['event_id'] : $event_id = "0";
add: $event_id = (string)@$_REQUEST['event_id'];
add: is_numeric( $event_id ) or $event_id = '0';
2.
do not change: if (isset($_REQUEST['mc_gross'])){
Plugins like this that refuse to test with WP_DEBUG on really make it hard for the rest of us the debug our sites, because they litter every page with garbage warnings about undefined variables. This plugin also makes almost no attempt to namespace itself, as others have noted in these support forums. Look at the many generic admin url’s it claims for itself:
On the other hand, it does work for us, and we paid for an add-on. This is the first real bug we have found. Would have been really easy for the devs to clear up if they had kept WP_DEBUG on when testing.