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Read the guideYou ask Microsoft 365 Copilot about a document you have open in another window and it replies that it could not find it. This is the most common Copilot complaint in enterprise tenants, and it is almost never about the file being missing. Copilot can only ground on content the signed-in account can already open, that has been indexed, that carries a supported format and label, and that sits under the size limit. Break any one of those and Copilot behaves as though the file does not exist rather than telling you why. This guide walks the checks in the order that resolves the most cases fastest, and flags the ones that need an administrator.
Copilot replies that it could not find the file, or returns results from a different document
File uploads into Copilot chat fail while the same file opens fine in OneDrive
Copilot works in Word and Excel but cannot reach anything in SharePoint
OneDrive indexing appears stuck or never initialises
Some files in a folder are readable and others are silently skipped
An agent returns an authentication or 'auth expired' style failure when reading a file
SharePoint and OneDrive as knowledge sources require an active Copilot licence on the account making the request. Without it, grounding on tenant files silently fails even though general chat still works.
Multi-account setups are a frequent culprit. Copilot only sees what the currently signed-in identity can open, so being signed into a personal account in one app and a work account in another produces exactly this symptom.
Grounding works on text-based formats (Word, PowerPoint, Excel, PDF, TXT, RTF, HTML and similar) under 150MB. Scanned image-only PDFs, unusual formats, and oversized files get skipped without an explanation.
If an administrator applies protection, legacy Information Rights Management, or restricts sharing on a document, Copilot will not ground responses on it even though the file still exists and you can open it directly.
Recently uploaded, moved, or re-permissioned files need to be indexed before Copilot can retrieve them. During that window Copilot genuinely cannot see the file, and reports of OneDrive indexing not initialising point at this.
When to try: First, before anything involving administrators.
Check the account picture in Word, Excel, Teams, the browser, and OneDrive. They must all be the work account that owns or has access to the files. Sign out of any personal account in the same app, then reload and retry the request.
When to try: When Copilot answers general questions but never finds any tenant file.
Open the Microsoft 365 account portal or ask your admin to confirm a Microsoft 365 Copilot licence is assigned to your user. SharePoint and OneDrive knowledge sources need it. If the licence was assigned recently, allow time and sign out and back in to refresh the token.
When to try: When only certain files are invisible to Copilot.
Navigate to the file in OneDrive or the SharePoint library in a browser and open it. If you cannot, this is a permissions issue and no Copilot setting will help. Request access or ask the owner to reshare, then retry once your access is confirmed.
When to try: When one specific file fails while others in the same folder work.
Confirm the file is a supported text-based format under 150MB. If it is a scanned PDF with no text layer, run OCR (Acrobat, or re-export from the source) before expecting Copilot to read it. Image-only PDFs are the most common silently-skipped file type.
When to try: When Copilot returns the wrong document instead of nothing.
Instead of describing the document, paste the direct link or use the file-picker so Copilot is pointed at an exact item rather than searching. This bypasses retrieval failures caused by weak search matching and immediately distinguishes a search problem from an access one.
When to try: When single-file requests succeed but batch ones fail.
Multi-file actions are constrained, and asking Copilot to reason over a large selection at once is a documented failure mode. Select no more than five files per request and chain the work across several prompts.
When to try: When the file opens normally for you but Copilot consistently refuses to use it.
Share the exact file with your administrator and ask whether a sensitivity label, legacy IRM protection, or a restricted sharing policy applies. These block Copilot grounding by design. The admin can confirm from the compliance portal whether the label permits Copilot processing.
When to try: For files that are brand new or were just relocated.
For a file uploaded, moved, or re-shared in the last day, give indexing time and retry. If OneDrive indexing appears permanently stuck for a user, that is an admin and support case, not something you can force from the client side.
Keep every Microsoft app signed into the same work account
Store Copilot-relevant documents in supported text formats and OCR scanned PDFs before uploading
Ask an admin before applying restrictive sensitivity labels to documents teams need Copilot to read
Reference files by link or file-picker rather than by description when precision matters
Escalate to your Microsoft 365 administrator when licensing, sensitivity labels, IRM, or tenant sharing policy are involved, since none of these can be changed from the client. Open a Microsoft support case when OneDrive indexing never initialises for a licensed user, or when file reads fail with authentication errors that persist across sign-outs and devices.
Most often because the signed-in account lacks an active Copilot licence, is not the account with access to the file, or the file is an unsupported format, over 150MB, or has not finished indexing. Sensitivity labels and IRM protection also block grounding by design.
Text-based formats including Word, PowerPoint, Excel, PDF, TXT, RTF and HTML, under 150MB. Scanned image-only PDFs with no text layer are a common silent failure, so run OCR on them first.
No. Copilot is limited to content the signed-in user can already access. If a file has been moved, unshared, or had its permissions changed, Copilot loses access at the same moment you do.
Multi-file requests are constrained, and selecting a large batch is a documented failure mode. Keep multi-file actions to five files at a time and split larger jobs across multiple prompts.
They can. Certain protections, legacy IRM, and tightened sharing policies prevent Copilot grounding on a document even though you can still open it yourself. Only an administrator can confirm and change the applied label.