Tech giant blames ‘user error, not AI error’ for incident in December involving its Kiro tool

Amazon’s cloud unit has suffered at least two outages due to errors involving its own AI tools, leading some employees to raise doubts about the US tech giant’s push to roll out these coding assistants.

Amazon Web Services experienced a 13-hour interruption to one system used by its customers in mid-December after engineers allowed its Kiro AI coding tool to make certain changes, according to four people familiar with the matter.

The people said the agentic tool, which can take autonomous actions on behalf of users, determined that the best course of action was to “delete and recreate the environment”.

Amazon posted an internal postmortem about the “outage” of the AWS system, which lets customers explore the costs of its services.

Multiple Amazon employees told the FT that this was the second occasion in recent months in which one of the group’s AI tools had been at the centre of a service disruption.

“We’ve already seen at least two production outages [in the past few months],” said one senior AWS employee. “The engineers let the AI [agent] resolve an issue without intervention. The outages were small but entirely foreseeable.”

AWS, which accounts for 60 per cent of Amazon’s operating profits, is seeking to build and deploy AI tools including “agents” capable of taking actions independently based on human instructions.

Like many Big Tech companies, it is seeking to sell this technology to outside customers. The incidents highlight the risk that these nascent AI tools can misbehave and cause disruptions.

Amazon said it was a “coincidence that AI tools were involved” and that “the same issue could occur with any developer tool or manual action”.

“In both instances, this was user error, not AI error,” Amazon said, adding that it had not seen evidence that mistakes were more common with AI tools.

The company said the incident in December was an “extremely limited event” affecting only a single service in parts of mainland China. Amazon added that the second incident did not have an impact on a “customer facing AWS service”.

Neither disruption was anywhere near as severe as a 15-hour AWS outage in October 2025 that forced multiple customers’ apps and websites offline — including OpenAI’s ChatGPT.

Employees said the group’s AI tools were treated as an extension of an operator and given the same permissions. In these two cases, the engineers involved did not require a second person’s approval before making changes, as would normally be the case.

Amazon said that by default its Kiro tool “requests authorisation before taking any action” but said the engineer involved in the December incident had “broader permissions than expected — a user access control issue, not an AI autonomy issue”.

AWS launched Kiro in July. It said the coding assistant would advance beyond “vibe coding” — which allows users to quickly build applications — to instead write code based on a set of specifications.

The group had earlier relied on its Amazon Q Developer product, an AI-enabled chatbot, to help engineers write code. This was involved in the earlier outage, three of the employees said.

Some Amazon employees said they were still sceptical of AI tools’ utility for the bulk of their work given the risk of error. They added that the company had set a target for 80 per cent of developers to use AI for coding tasks at least once a week and was closely tracking adoption.

Amazon said it was experiencing strong customer growth for Kiro and that it wanted customers and employees to benefit from efficiency gains.

“Following the December incident, AWS implemented numerous safeguards”, including mandatory peer review and staff training, Amazon added.

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