Anthropic’s freshly released AI models Claude Mythos 5.1 and Claude Fable 5.1 are temporarily down a day after launch, along with Claude Opus 5.
Since this afternoon, users have been seeing an error message in the Claude chat window, one day after the launch of the new Claude Mythos 5.1 and Claude Fable 5.1. The company shared this on its status page. Claude has since identified the cause of the problem and implemented a solution.
Day after launch #
On September 2, Anthropic announced its latest models Claude Mythos 5.1 and Claude Fable 5.1, “the world’s most advanced models for coding and knowledge work,” according to the company. That launch appears to be facing some hurdles, as issues are emerging with both models, as well as Claude Opus 5. More specifically, users are seeing the message below in the chat window.
Anthropic has now identified and resolved the cause of the problem. The company is keeping users informed via the status page.