Don't know what this is yet, but I found it in payments.error:
May 2 23:03:22 payments1003 astropay_gateway: Exception in GatewayPage constructor with adapter class AstropayAdapter: No supported currencies for GB
#0 /X/payments/extensions/DonationInterface/gateway_common/DataValidator.php(318): AstropayAdapter->getCurrencies(Array)
#1 /X/payments/extensions/DonationInterface/gateway_common/DonationData.php(977): DataValidator::validate(Object(AstropayAdapter), Array, Array)
#2 /X/payments/extensions/DonationInterface/gateway_common/DonationData.php(344): DonationData->getValidationErrors()
#3 /X/payments/extensions/DonationInterface/gateway_common/DonationData.php(147): DonationData->normalize()
#4 /X/payments/extensions/DonationInterface/gateway_common/DonationData.php(115): DonationData->populateData(NULL)
#5 /X/payments/extensions/DonationInterface/gateway_common/gateway.adapter.php(268): DonationData->__construct(Object(AstropayAdapter), NULL)
#6 /X/payments/extensions/DonationInterface/gateway_common/GatewayPage.php(65): GatewayAdapter->__construct()
#7 /X/payments/includes/specialpage/SpecialPageFactory.php(410): GatewayPage->__construct()
#8 /X/payments/includes/specialpage/SpecialPageFactory.php(538): SpecialPageFactory::getPage('AstropayGateway')
#9 /X/payments/includes/MediaWiki.php(267): SpecialPageFactory::executePath(Object(Title), Object(RequestContext))
#10 X//payments/includes/MediaWiki.php(566): MediaWiki->performRequest()
#11 X//payments/includes/MediaWiki.php(414): MediaWiki->main()
#12 X//payments/index.php(41): MediaWiki->run()
#13 {main}