“Amazon Secure Token Service (STS) experienced elevated error rates between 11:49 AM and 2:10 PM PDT [on June 13, 2023] with three distinct periods of impact.” We saw significant impact across our stack as a result of this outage impacting STS; in addition a very wide swathe of AWS services (way more than in this postmortem note!) were reported as impacted. I still can’t get over that STS (the security token service, used by most modern AWS setups to gain tokens to use other AWS services) is reliant on Lambda. These foundational services are supposed to be rock-solid and built with conservative tech choices. Disappointing.