When you try to sign in to Copilot in Microsoft 365, you may see error AADSTS50105. This error means the user account is not assigned to the required license or application role. The error prevents access to Copilot features in apps like Word, Excel, and Teams. This article explains the root cause and provides step-by-step … Read more
When you upload a file to Copilot in Microsoft 365, you may see an HTTP 413 error that stops the process. This error means the server rejected the file because its size exceeds a defined limit. The root cause is typically a restriction in the Microsoft 365 tenant configuration or a local proxy setting that … Read more
Official documentation checked October 14, 2026. A “Service Principal Not Found” message while administering Copilot needs investigation of the actual directory object named by the failing operation. The banner alone is not enough to identify a universal missing “Copilot” application, and it does not justify creating one with an ID copied from an unrelated example. … Read more
Official documentation checked October 14, 2026. If Copilot in PowerPoint stays on “Initializing,” start by finding out whether the failure affects one presentation, the desktop app, or the account across devices. The spinner alone does not identify a broken license cache or prove that a particular Microsoft Graph request failed. This guide covers PowerPoint for … Read more
Official documentation checked October 14, 2026. AADSTS50158 means an external security challenge is involved in the sign-in flow. It can appear when the user is redirected to terms of use or an external authentication provider. Importantly, the code alone does not prove that the overall sign-in failed. Do not start by excluding Copilot from Conditional … Read more
Official documentation checked October 14, 2026. If Copilot begins reporting invalid_grant after a work-account password reset, first try a fresh sign-in in the affected application. A revoked or stale refresh token is one possible cause, but the error does not prove that every Microsoft 365 cache needs deleting. Save your work before signing out. Do … Read more
Official documentation checked October 14, 2026. If Microsoft 365 Copilot fails only while a corporate VPN is connected, the network path is a useful lead, not a complete diagnosis. DNS, routing, proxy authentication, TLS inspection, blocked WebSockets, and access policy can produce similar symptoms. Keep the managed VPN and security configuration intact while collecting evidence. … Read more
Official documentation checked October 14, 2026. A Copilot sign-in failure on Windows 11 is not automatically a Web Account Manager (WAM) failure. First identify the app, account type and full error. In particular, do not disconnect a managed work account or remove all Microsoft accounts just because a sign-in window says “Something went wrong.” 1. … Read more
If you see a “TLS Handshake Failed” error when trying to use Copilot in Microsoft 365 apps on an older Windows client, your connection is being blocked before Copilot can respond. This error means the secure communication channel between your device and Microsoft servers could not be established. The root cause is almost always an … Read more
When you use Copilot in Microsoft 365, you may see the error AADSTS9002313 with the message Invalid Request. This error stops Copilot from generating responses, drafting documents, or accessing your data. The cause is almost always a malformed authentication token or a mismatch in the token request parameters sent by the client app to Azure … Read more