When you try to use Copilot in Microsoft 365 apps or on Windows, you may see the error message “WinHTTP Error 12175” followed by “Certificate Revocation Check Failure.” This error prevents Copilot from connecting to Microsoft servers, blocking chat, drafting, and summarization features. The cause is a local system setting that disables or interferes with … 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 The cause is often a corrupted add-in registration, a damaged Word startup state, or an outdated Microsoft 365 installation.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
When you use Copilot inside Microsoft 365 apps on a corporate network, you may see the error message “Self-Signed Certificate in Chain.” This error stops Copilot from generating responses or connecting to the Microsoft Graph. The root cause is a corporate proxy or network security appliance that intercepts HTTPS traffic and replaces Microsoft’s certificate with … 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
When you try to use Copilot in Microsoft 365, you may see an error message containing the code AADSTS530005. This error indicates that a Conditional Access policy is blocking the application from accessing Microsoft Graph resources. The policy is usually set by your IT administrator to control which apps can access corporate data. This article … Read more
When you run Copilot on a Linux client, you may see connection errors that prevent the service from authenticating with Microsoft servers. The root cause is often a missing or outdated CA certificate bundle on the Linux system. Copilot relies on trusted root certificates to verify the identity of Microsoft endpoints. This article explains why … 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