Four major AI models suffer rare overlapping downtime

Cloud-based AI models operated by OpenAI, Anthropic, xAI, and Google suffered a rare and overlapping set of significant service interruptions over a period of hours Thursday morning.

Anthropic first reported a “partial outage” related to “elevated errors on requests to Claude Mythos 5.1, Claude Fable 5.1, and Claude Opus 5” at 9:23 am (all times Eastern). The company reported that it had “identified the cause” of the error roughly 15 minutes later, before reporting that “a fix has been deployed” and the issue was resolved by 12:16 pm. A separate incident report indicated “elevated errors on requests to Claude Sonnet 5” for a brief period just after noon.

OpenAI, meanwhile, reported “elevated errors across ChatGPT and Codex” were resulting in “degraded performance” as of 10:43 am Thursday morning. A mitigation put in place a little more than half an hour later led to the issue being marked as “resolved” by 12:55 pm.

As of this writing, xAI’s Grok currently displays a user-facing error message that the model “is experiencing issues” and that the company is “working on restoring service as quickly as possible.” User-submitted reports from DownDetector regarding Grok shot up from less than 10 just before 9 am to 1,365 by 9:45 am and have fallen to 273 as of this writing.

While Google has not publicly acknowledged any issues with its Gemini model, reports of problems on DownDetector similarly spiked from just 23 around 10:30 am to 412 just after 11 am. Data collected by API checker StatusGator also shows what it terms a “likely outage” for the Gemini API between 10:45 and 11:15 a.m. before the status returned to normal.

Other major Internet services, including Amazon Web Services, Microsoft Azure, and Cloudflare, have not reported any major issues as of press time Thursday, though issue reports on DownDetector did spike somewhat for all three this morning.

While the affected frontier models go down occasionally, having all four experience interruptions in the same short period is practically unheard of. Claude reports 99.4 percent uptime for its services over the last 90 days and last reported a similar three-hour “partial outage” on August 24. OpenAI reports 99.63 percent uptime for ChatGPT and 100 percent uptime for ChatGPT Codex in the same period. ChatGPT’s so-called “Work Mode” reported an hours-long period of “elevated latency” on August 31.