upon upgrade from 4.7.31 to 5.3 the site could not load any civi pages, it would give a generic error message.
in the log I see:
Civi\Payment\Exception\PaymentProcessorException: CRM_Core_Payment_PayPalImpl: Payment processor type is not defined! in CRM_Core_Payment_PayPalImpl->__construct() (line 73 of /var/www/xxxxxx/sites/all/modules/civicrm/CRM/Core/Payment/PayPalImpl.php).
but this site does not use paypal, it uses authorizenet so I have no idea why this is causing a fatal error
my temp workaround was to just comment out line 73 of PayPalImpl.php but I'll need to verify that payments still work. Anyone else have a similar issue with 5.3?