Official documentation checked October 14, 2026. WinHTTP error 12175 means that Windows found a problem with the server’s TLS certificate. It does not, on its own, identify a failed revocation check or prove a Copilot-specific defect. Do not delete trusted roots, disable certificate validation, or remove security updates to make the connection succeed. 1. Identify … Read more
When you open Microsoft Word, the Copilot add-in may fail to load and display COM error 0x80004005. This error indicates an unspecified failure in the Component Object Model layer that prevents the add-in from initializing. The cause is often a corrupted add-in registration, a damaged Word startup state, or an outdated Microsoft 365 installation. This … Read more
Official documentation checked October 14, 2026. A self-signed-certificate or untrusted-chain error means the client could not establish the required certificate trust. A corporate inspection proxy is one possible cause, but the error is not proof that every certificate shown should be trusted. Identify the Copilot product, client, and certificate issuer before changing a trust store. … Read more
When you try to sign in to Copilot in Microsoft 365, you may see an error message that reads AADSTS500011: The resource principal named was not found in the tenant. This error means Azure Active Directory cannot locate the service principal for the Copilot application in your tenant. The root cause is usually a missing … Read more
When you open Copilot in Safari on a Mac, the sidebar may appear blank with no content, no chat input field, and no error message. This occurs because Safari’s default privacy settings block cross-site cookies and local storage that Copilot requires to load its interface. This article explains why the sidebar stays empty and provides … Read more
When you try to sign in to Copilot in Microsoft 365, you might see the error AADSTS500133: Assertion not valid yet. This error means the security token your device sent to Microsoft Entra ID was created with a time stamp that is before the current server time. The cause is almost always a clock mismatch … Read more
You open Copilot in Firefox Mobile’s Webview, type a prompt, and tap Submit. The page freezes, reloads, or closes entirely. This crash happens because Firefox Mobile’s Webview engine handles certain WebSocket and service-worker connections differently than Chromium-based browsers. This article explains the root cause and provides three working fixes you can apply now. Key Takeaways: … Read more
Official documentation checked October 14, 2026. If a Copilot sign-in screen shows AADSTS530005, save the complete error details before changing anything. We could not verify a definition for that exact number in Microsoft’s public Entra error reference when checking this article. The number alone does not establish that an application filter or device-compliance policy is … Read more
Official documentation checked October 14, 2026. A missing CA bundle can cause TLS failures on Linux, but “Copilot on Linux” does not identify one universal application or configuration file. First establish whether the failure is in a browser-based Microsoft Copilot session, a GitHub Copilot editor extension, or another client. The repair must apply to the … Read more
Copilot on Windows on ARM64 devices may fail to initialize, showing a blank pane or an error message that Copilot cannot start. This problem often occurs because the Copilot app or its dependencies are not fully compatible with the ARM64 architecture, or because the required Windows components are missing or outdated. This article explains the … Read more