Over the weekend, unrelated to any changes on our part, some of our AWS-related automated tests started to fail. A simple manual check revealed that the same API user could successfully authenticate against AWS through some API clients, but other, older clients would fail to authenticate and get a 401 error. Upgrading the culprit test clients to a recent version fixed this issue instantly.
Our speculation about the source of the change is that the AWS team must have taken one more step towards deprecating their version 2 authentication in favor of version 4, rendering older clients incompatible. But so far we were not able to find any reference to this in any Amazon online documentation.
Just one more wake-up call demonstrating the importance of keeping third-party libraries up-to-date…
