Copilot in Word can't read chat attachments; Word for web file picker shows “no token obtained”

Summary of the issue

I am seeing a persistent failure with Copilot attachments specifically inside Microsoft Word. Copilot in Word desktop and Word for the web can recognize an uploaded chat attachment by filename or OneDrive URL, but it cannot read the file contents. It reports the uploaded file as empty, corrupted, or in a format it cannot process. The same files are successfully read by standalone Microsoft 365 Copilot Chat using the same Microsoft account, and file uploads also work in Excel Copilot and PowerPoint Copilot.  Failure started 10 days ago, with no obvious changes in settings on my end.

The most useful diagnostic clue so far is that Word for the web’s Copilot attachment/file-picker path has also failed before any file was selected, showing “Something went wrong, please try again or refresh the page, no token obtained.” In Chrome, Word for the web produced a SharePoint-style error page with a correlation ID. This makes the issue look less like a bad file or local Word installation problem and more like a Word Copilot attachment-picker, OneDrive/SharePoint authorization-token, or file-handoff problem.

Environment and scope

• Windows 11, Pro. Microsoft Word desktop: issue reproduced after updating Office and Windows.
• Word for the web: issue reproduced in Edge, Edge InPrivate, and Chrome.
• Standalone Microsoft 365 Copilot Chat / copilot.microsoft.com / m365.cloud.microsoft/chat: uploaded files can be read successfully with the same Microsoft account.
• Excel Copilot and PowerPoint Copilot: uploaded files work.
• OneDrive in Chrome: upload/download and file access work normally with the same account.
• Same Microsoft account used throughout.
• File types tested include tiny TXT files, PDFs, and DOCX files, including a complex DOCX.
• Copilot in Word can read the active Word document normally; the failure is limited to files uploaded as Copilot chat attachments inside Word.

Observed behavior

In Word desktop, Copilot chat accepts or recognizes the attachment metadata, including filename and sometimes a OneDrive URL, but when asked to read or summarize the file it says the file appears to be empty, corrupted, or in a format it cannot process. This happens even with a very small TXT test file.

In Word for the web, the same general failure occurs. In one clean test, I created a brand-new blank Word document in Word for the web, opened Copilot, attached a tiny TXT file, and asked what the uploaded TXT file said. Copilot responded: “The uploaded file ingestion_test_731_1915.txt appears to be empty, corrupted, or in a format I can’t process, so I can’t read any text from it.”

In another Word for the web test, clicking Copilot’s “+” attachment button and choosing either “My Files” or “Recent” opened a mostly blank window saying: “Something went wrong, please try again or refresh the page, no token obtained.” This occurred before any file was selected.

In Chrome, Word for the web produced this error when trying to use the Copilot attachment flow: “Sorry, something went wrong. An unexpected error has occurred. Technical Details: Troubleshoot issues with Microsoft SharePoint Foundation.” The error included Correlation ID 64062ea2-3083-8000-a0f7-fbf4f6bb617d and Date/Time 8/4/2026 12:21:38 PM.

Evidence matrix

Troubleshooting already tried

• Updated Microsoft Office / Microsoft 365 desktop apps.
• Updated Windows.
• Restarted Word multiple times.
• Restarted the computer multiple times.
• Signed out and signed back in.
• Confirmed that the same Microsoft account is being used; there is only one Microsoft account involved.
• Toggled connected experiences off and back on, including restarts between changes.
• Started Word in Safe Mode. In Safe Mode, Copilot chat opened but did not activate properly; the Copilot pane appeared to cycle in the background and sub-windows were blank/unusable.
• Tested with a brand-new blank Word document in Word for the web.
• Tested in Edge, Edge InPrivate, and Chrome.
• Tested with very small TXT files as well as PDF and DOCX files.
• Confirmed OneDrive itself works normally in Chrome by uploading and accessing files successfully.
• Confirmed standalone Copilot and Excel/PowerPoint Copilot can process uploaded files successfully.

Why this does not look like a local file or browser problem

The same uploaded files work in standalone Microsoft 365 Copilot Chat, and OneDrive upload/download works normally. The issue also reproduces across Word desktop and Word for the web, across multiple browsers, and with a brand-new blank Word document. Because Word Copilot can read the active document but cannot acquire or process uploaded chat attachments, the failure appears isolated to the Word-integrated Copilot attachment picker, authorization-token acquisition, or OneDrive/SharePoint file-handoff path.

Most likely failure area

My current working theory is that Word-integrated Copilot is failing to obtain or pass the required SharePoint/OneDrive authorization token for Copilot chat attachments. The “no token obtained” message and the SharePoint Foundation correlation ID point toward the file-picker or backend handoff path rather than file contents. It may be account-specific, feature-flight/routing-specific, or a Microsoft-side regression affecting Word Copilot attachment handling.

Request for help

Has anyone seen Word Copilot attachments fail in this way while standalone Copilot, OneDrive, Excel Copilot, and PowerPoint Copilot all still work? Are there known Word Copilot attachment-picker, OneDrive/SharePoint token, or feature-routing issues that can affect only Word-integrated Copilot? If Microsoft support or engineering can trace backend logs, the most relevant correlation ID I have is 64062ea2-3083-8000-a0f7-fbf4f6bb617d from 8/4/2026 at 12:21:38 PM in Word for the web in Chrome.

I would especially appreciate suggestions for anything beyond the standard local troubleshooting already tried. At this point, the pattern suggests the next useful step is probably backend investigation of the Word Copilot attachment/file-picker authorization flow rather than more file-format testing or local repair.