M365 Copilot desktpp & Web

The described behavior matches a service-side issue with file handling in Microsoft 365 Copilot rather than a problem with the individual files, licensing, or account configuration, especially since:

• The same Word/PDF files work correctly with Copilot inside Word.
• Multiple file types (.docx, .pdf, etc.) fail when uploaded to the Microsoft 365 Copilot desktop and web apps.
• Files from both local storage and OneDrive fail in the same way.

From the available information, the main checks that can be done client-side are already covered:

1. File format and conversion
   • Copilot in Microsoft 365 supports .docx, .doc, .pdf, .txt, .rtf, .html, .htm for Word scenarios and .pptx, .ppt, .pdf, .docx for PowerPoint, and can work with these when stored in OneDrive or uploaded.
   • If any file was in an older or unusual format, saving it as .docx or .pdf is the recommended mitigation, but this has already effectively been ruled out by the fact that these same files worked yesterday and still work in Word Copilot.
2. File location and permissions
   • Copilot requires uploaded or cloud-hosted files; local paths are not directly supported for some scenarios. Using OneDrive and confirming access/permissions is the correct step and has already been tried.
   • A permissions issue would typically affect only some files or locations, not all uploads across both desktop and web Copilot.
3. File size/complexity
   • Very large or complex documents can cause issues; splitting them into smaller files is recommended. However, the failure across multiple files (including ones that previously worked) indicates a broader issue.

Given that:

• Copilot in Word continues to function with the same documents.
• Both the Microsoft 365 Copilot desktop app and the web experience at m365.cloud.microsoft fail to read any uploaded files.

The most likely cause is a temporary or ongoing backend/service regression or configuration issue affecting file upload/processing for Microsoft 365 Copilot Chat, not something that can be fixed by local configuration.

Recommended actions:

1. Re-validate basic conditions (quick checks)
   • Confirm the files are in supported formats (.docx, .pdf, .pptx, etc.) and not zero-byte or obviously corrupted.
   • Try a very small, simple test document (e.g., a new one-page .docx saved to OneDrive) to confirm the behavior is consistent.
2. Use supported upload paths
   • Prefer uploading from OneDrive or other cloud locations rather than local paths, as recommended in the troubleshooting guidance.
3. Reduce complexity for testing
   • For a test, create a short document or small PDF and upload it to Copilot Chat to rule out size/complexity as a factor.
4. If the issue persists across all files and devices
   • Treat this as a service-side issue with Microsoft 365 Copilot file processing.
   • Collect examples (file types, approximate sizes, timestamps, tenant/region) and raise a support ticket with Microsoft 365 support so the backend team can check for known incidents or regressions affecting file upload and parsing.

Because Copilot in Word is functioning and the environment checks (license, account, OneDrive) are already validated, further remediation requires investigation by Microsoft support rather than additional client-side changes.

References:

• File formats supported by Microsoft 365 Copilot