Copilot Not Working

Fix Copilot File Size Exceeds Maximum Upload Limit Error

Nimra Malik Sep 28, 2026 869 views

Question details

Users are unable to upload documents to Microsoft Copilot due to a false maximum size limit error, even when files are very small.

How to Fix Copilot 'File Size Exceeds Maximum Upload Limit' Error

Product: Microsoft Copilot
Device & OS: not provided
Scenario: Uploading documents such as PDFs or Word files to Copilot for AI analysis and summarization.
Observed behavior: Copilot rejects the document upload and displays an error indicating the file size exceeds the maximum limit, despite the file being well under the documented limits (e.g., failing on a 1.5 MB file).

Before you start

Verify the exact file size of your document and ensure it is not password-protected, as encrypted files can sometimes trigger false upload errors in Copilot.

Solution 1Recommended

Use a Local File and Switch Browsers

Bypass potential OneDrive syncing issues and browser cache bugs by downloading the file locally and uploading it through a private browsing session.

Copilot's web interface can sometimes struggle to process files linked directly from cloud storage or may be hindered by outdated browser cache, resulting in false file size errors.

Download the file locally

If you are trying to upload a file directly from OneDrive or SharePoint, download a copy of the document to your computer's local drive first.

Open a private browsing window

Launch your web browser and open an Incognito or InPrivate window to ensure no conflicting extensions or cached data interfere with the session.

Upload to Copilot

Navigate to Microsoft Copilot, log in to your account, and attempt to upload the local copy of the small file again.

Account Limits Vary: Ensure you know your specific account limits. Copilot Pro, Copilot Online, and Copilot Studio all have different baseline file size restrictions.

Solution 2

Verify Enterprise Licensing and Permissions

For corporate or educational accounts, file upload limits and permissions are managed by IT administrators and may have been recently restricted.

Solution 3

Report the Bug to Microsoft Support

If files under 1 MB are consistently failing across different browsers, it is likely a backend bug requiring Microsoft's direct intervention.

Free Microsoft Office alternative

Analyze Documents Effortlessly with WPS AI

If Microsoft Copilot continues to block your document uploads with arbitrary file size errors, consider switching to WPS Office. WPS AI is seamlessly integrated into the free, lightweight WPS Office suite, allowing you to summarize, chat with, and analyze your PDFs and documents directly on your desktop without frustrating online upload limits.

Seamlessly analyze and summarize documents using built-in WPS AI capabilities.Fully compatible with Microsoft Office formats (DOCX, XLSX, PPTX) and PDF files.Lightweight, fast, and eliminates the need to upload sensitive files to a web browser interface.Completely free to download with a familiar, easy-to-use user interface.

Frequently Asked Questions

What is the actual maximum file upload size for Microsoft Copilot?

The maximum file size limit depends entirely on your specific subscription tier and the Copilot product you are using (e.g., Copilot Pro vs. Copilot Studio). Always check Microsoft's official documentation for your specific tier, as limits frequently change.

Why does Copilot reject my small PDF file claiming it's too large?

This is often caused by a known glitch in Copilot's web interface, temporary server degradation, or browser caching issues. It can also occur if the PDF contains complex embedded elements or encryption that Copilot cannot parse, triggering a generic size error.

Does the file storage location affect Copilot uploads?

Yes. Users frequently report that attempting to link or upload files directly from OneDrive can trigger false size limits or authentication errors. Downloading the file to your local computer and uploading it directly usually resolves this issue.

Microsoft Copilot Issues