Android users are experiencing authentication issues with the Gmail app when trying to access Microsoft 365 or Exchange Online accounts, preventing access to work emails on mobile devices. This issue affects users across various devices, including Pixel, Samsung, Sony, OnePlus, Xiaomi, and Motorola, with reports from over 500 end users across 50 companies. The error message displayed is: “Check your account info or switch to modern authentication below. If you need help, contact your IT admin.” Attempts to delete and re-add accounts often worsen the situation. The problem may be linked to Microsoft enforcing Exchange ActiveSync (EAS) protocols, specifically a change implemented on March 1, 2026, requiring EAS version 16.1, which Gmail cannot meet. Outlook remains unaffected due to its use of a different sync protocol. Users have attempted various temporary solutions, such as clearing app cache and wiping app data, but these have proven unreliable. The most stable workaround currently recommended is to switch to the Outlook app for Android. Neither Google nor Microsoft has publicly addressed the authentication issues.