That took care of the Institutional subscriptions problem and the associated Error 500, thanks @asmecher!
Installation of 3.1.2.1 will have to wait for now. But it doesn’t seem to be much to gain, going from 3.1.2.0? I mean, no security patches, just some cosmetics and added functionality, afaict?
As for the PayPal error message when attempting to purchase an individual subscription, the PHP log contains POST and GET entries with some error labels it seems:
GET /purchaseSubscription/individual HTTP/2" 200 4913 “/about/subscriptions” “Mozilla/5.0 (Wind$
POST /payPurchaseSubscription/individual/ HTTP/2” 200 4704 "/user/purchaseSubscription/individu$
I am not good with PHP or its error structure - do these logs tell you anything useful?
Also, I noticed a pertaining PHP Warning in the server’s error_log - perhaps of use too:
PHP Warning: Declaration of IndividualSubscriptionsGridHandler::renderFilter($request) should be compatible with SubscriptionsGridHandler::renderFilter($request, $filterData = Array) in /controllers/grid/subscriptions/IndividualSubscriptionsGridHandler.inc.php on line 20
Again, although the REST API credential are all correctly pasted from developer.paypal.com, perhaps I messed up with their webhooks? What is the correct format for a PayPal webhook on an OJS3 installation anyway? I don’t recall seeing that explained anywhere really. Provided that they are critical to have, that is. Additionally, I do have restful_urls = On in config.inc.php, so perhaps this interferes with their webhook structure?