Our card processor deployed an update yesterday that has subsequently broken our ability to submit transactions (all attempts are returning an authentication error). We are attempting to resolve the situation as quickly as possible.
UPDATE: After dumping the raw response we’re getting from the processor, it turns out to be a “500 Internal Server Error” message, so the problem is definitely not with us. We have contacted them for resolution.
UPDATE 2: There is still no resolution at this time. We have changed our PayPal account to allow credit card payments without requiring a PayPal account.
UPDATE 3: It looks like the problem is an extra field in the response string toward the end where the MD5 checksum field is; the checksum was shifted up one offset, resulting in our side looking at a blank field. This does not match the authorize.net guide, so we are still working with the processor to find out why there is an extra field in the response. The critical fields (trans id, invoice number, authorization, etc.) are in the correct location, so as a workaround we are disabling the checksum test.
Due to this issue, auto-pay did not run, and some other transactions were voided. We are reviewing everything since November 2 and will manually run auto-pay for accounts that were affected or contact those who need to re-submit a payment.