SPFx Copilot Component fails to load in Microsoft 365 Copilot due to REST calls returning 403 Forbidden

[HarminderSethi]

Target SharePoint environment

SharePoint Online

What SharePoint development model, framework, SDK or API is this about?

💥 SharePoint Framework

Developer environment

None

What browser(s) / client(s) have you tested

• 💥 Internet Explorer
• 💥 Microsoft Edge
• 💥 Google Chrome
• 💥 FireFox
• 💥 Safari
• mobile (iOS/iPadOS)
• mobile (Android)
• not applicable
• other (enter in the "Additional environment details" area below)

Additional environment details

• SPFx version 1.24.0-beta.2
• Node.js version 22.14.0

Describe the bug / error

I am developing an SPFx Copilot Component and experiencing an issue where the component fails to load inside Microsoft 365 Copilot.

The UI displays the following message:

While investigating the browser network trace, I noticed that the following REST API calls are returning 403 Forbidden:
/_api/contextinfo
/_api/web/GetClientSideComponents

Steps to reproduce

1. Deploy an SPFx Copilot Component to SharePoint Online.
2. Open the agent/component inside Copilot.
3. Observe that the component fails to load.
4. Check browser Developer Tools → Network tab.
5. Notice 403 responses from the REST endpoints listed above.

Expected behavior

The SPFx Copilot Component should load successfully within Microsoft 365 Copilot,

[jansenbe]

Harminder Singh (@HarminderSethi) : can you try the resolution steps I wrote in #11006 and see if that unblocks you?

[HarminderSethi]

Bert Jansen (@jansenbe) It worked. It is strange that on one machine it works without opening the SharePoint site page and on other it does not.

Also most of the times I get below error on first call to copilot component.

[jansenbe]

Thx Harminder Singh (@HarminderSethi) . Feels weird that the service worker is not automatically upgrading in background, we'll investigate this.

regarding the first run error: if you happen to have a HAR file and console log output of a failing run then please share