Major artificial intelligence platforms ChatGPT, Claude and Grok, along with several Microsoft 365 services, were gradually recovering on Thursday after technical problems disrupted access for users worldwide.
Outage-monitoring platform Downdetector recorded thousands of reports involving the three AI services at the height of the disruption. Problems were also reported with Google’s Gemini, although the extent and duration of the disruption varied across platforms.
Claude reported that its Opus 4.8 and Opus 5 models were affected, while problems involving Claude Mythos 5.1, Claude Fable 5.1 and Claude Opus 5 were subsequently resolved.
Microsoft, meanwhile, traced the disruption affecting its cloud-based email and other services to a problem with a core authentication configuration within its Exchange Online infrastructure.
The company initially identified a common pattern of authentication failures and protocol connectivity issues. Engineers conducted manual tests on individual servers before rolling out remedial measures across the affected infrastructure.
“We continue to see gradual improvements to the service as our mitigation actions are applied,” Microsoft said, warning that some users could continue experiencing intermittent disruption and delays in email delivery during the recovery.
The authentication problem also affected services beyond Exchange Online, including OneDrive for Business, SharePoint Online, Teams, Microsoft Purview, and Microsoft Defender XDR.
Downdetector showed a sharp increase in complaints during the disruption, although the platform’s figures are based on user-submitted reports and do not represent the total number of people affected.
Services gradually returned to normal on Thursday as the affected companies continued their recovery efforts.