Copilot Studio agents problems connecting to Sharepoint knowledge source

Hello,

Since this is a sudden regression affecting multiple agents simultaneously across your tenant (agents that previously worked), one question first:

Which Copilot Studio experience did you use to build your agents — the classic experience (canvas with topics) or the new experience (production-ready preview)?

Microsoft's documentation confirms that some SharePoint features are not yet available in the new experience, and authentication and retrieval behaviors can differ between the two...

This will help narrow down the diagnosis.

In parallel, here are the points you can check :

- If a tenant admin recently enabled Restricted SharePoint Search, SharePoint access is completely blocked for Copilot Studio agents. Check : SharePoint Admin Center > Search > Restricted SharePoint Search.

- If a SharePoint site or folder used as a knowledge source was recently renamed, the existing source link breaks and causes a permission gap the agent silently returns no results.

Verify that the SharePoint URLs configured in your agents still match the current site/folder names.

- Check your M365 Admin Center > Health > Service health for any active incidents related to Copilot Studio or Microsoft Search.

- Verify that your Entra ID app registration still has Sites.Read.All and Files.Read.All granted. If consent was silently revoked, the agent returns no results without surfacing any error.

- A service-side indexing change can silently interrupt SharePoint content retrieval with no visible alert.

The recommended next step is to open a support ticket via the M365 Admin Center, referencing the exact date the regression started, so Microsoft can correlate it with any service-side changes on their end.

Hope you find this useful