Claude went down on Friday morning — or more precisely, its front door did. Anthropic confirmed an authentication outage affecting claude.ai, Claude Code, the developer console and Claude Cowork, with the incident logged on its status page at 09:58 UTC (04:58 EST). The models themselves were fine; getting to them was the problem.

The shape of the failure was unusual. The Claude API stayed operational throughout, which meant developers calling Anthropic’s models by API key could keep working while anyone who needed to sign in — through the website, the coding tool, or the console — hit a wall. That split is what made the morning so strange: the service was up and down at the same time, depending on how you reached it.

Illustration of people staring at laptops and phones showing login error screens during a cloud service outage
Illustration: AI-generated for AI Frontier Post

What users saw#

The r/ClaudeAI discussion hub, posted by the subreddit’s moderator bot at 5:00 AM EST, turned into a live triage board within the hour. Users reported being signed out mid-session, asked to authenticate again out of nowhere, and blocked from logging back in. Claude Code users reported 403 authentication errors when the tool tried to connect. One team said its product had already switched to a fallback provider because the console route was failing for its users — a reminder that ‘API operational’ and ‘reachable’ are not the same thing when the login layer is down.

Recovery reports were mixed. Some people got back in within the hour; others were still locked out, and users in the thread called for Anthropic to issue a free usage reset for the lost time. As of the latest status check, Anthropic’s status page still showed only the initial investigating update — no cause, no estimated fix time.

Illustration of a data center control room with engineers under red alert glow during an AI service outage
Illustration: AI-generated for AI Frontier Post

A bad morning to lose your login#

The outage arrived on top of a second, unrelated failure. Microsoft’s Outlook, Teams and Exchange Online outage, which began on Thursday, dragged into a second day on Friday — and some Claude users found they could not complete the login loop because the two-factor codes and magic-link emails Anthropic sends were stuck in a downed Outlook. Anthropic has not linked its authentication problem to Microsoft’s, and the two incidents look separate: the Claude login failure hit people who never touch Microsoft tools.

There is a genuine Microsoft connection elsewhere on the status page, just not this one. Since Thursday afternoon, a separate incident has affected Claude’s Microsoft 365 connector — mail, calendar and search tools failing for most requests, with Claude for Outlook still affected. Anthropic attributes that one directly to a Microsoft 365 service incident. The authentication outage is listed as its own incident, with no cause named.

The pattern is the problem#

One outage is an incident; two in six weeks is a pattern. The September 29 partial outage hit nearly the whole Claude surface — claude.ai, Claude Code, the API and the console — and lasted roughly 40 minutes before a mitigation landed. This one is narrower, confined to authentication, but it is the latest in a string of sign-in problems for the company, and it struck during US morning hours, when developers are starting their day on Claude Code.

For casual users the cost is annoyance. For teams that build on Claude Code, the cost is a morning of stalled work — and a question about how much of their workflow depends on a login screen they do not control. The API staying up is the mitigation Anthropic can point to; the lesson for everyone else is to have a fallback provider configured before the morning they need one.

What to watch#

Anthropic has not publicly named a cause. The questions that matter now: does the company post a postmortem explaining what broke in authentication; does the status page clear to fully operational, and how long does recovery take for the users still locked out; and does the company address the thread’s call for a usage reset for the lost time.

For now, the practical advice is the boring kind: if you run Claude Code in production, keep a fallback provider configured and your API keys separate from console sessions. The models did not fail this morning. The door did.

Sources#