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How to Fix Unhandled Client Error When Uploading to SharePoint

Guest Writer Sep 28, 2026 869 views

Question details

The user is experiencing an unhandled client error while trying to upload files to SharePoint, which persists even after clearing the browser cache or restoring permissions.

How to Fix Unhandled Client Error When Uploading to SharePoint

Product: Microsoft SharePoint
Device & OS: not provided
Scenario: Uploading documents or files to Microsoft SharePoint.
Observed behavior: An unhandled client error blocks the file upload process, likely due to a Microsoft 365 service incident or tenant-specific configuration issue.

Before you start

Before escalating the issue, ensure your internet connection is stable and try uploading the file from an incognito or private browsing window to rule out any local browser extensions causing the error.

Solution 1Recommended

Check Microsoft 365 Service Health and Submit a Support Request

Since this error is often tied to widespread Microsoft 365 incidents or tenant issues, checking the Service Health Dashboard is the most effective approach.

This error is commonly related to Microsoft 365 service incidents (such as MO801333), which affect file-related operations across Microsoft 365 services. When a global service interruption occurs, client-side fixes like clearing caches will not work.

Contact your IT Administrator

Reach out to your organization's Microsoft 365 administrator or IT support team to report the specific upload error you are encountering.

Check the Service Health Dashboard

Ask the administrator to log into the Microsoft 365 admin center and navigate to Health > Service health to check for any active incidents affecting SharePoint Online.

Create a Support Request

If there is no known incident explaining the outage, the admin should navigate to Support > New service request in the Microsoft 365 admin center to open a ticket directly with Microsoft.

Check Microsoft 365 Service Health and Submit a Support Request

Save Locally: While waiting for Microsoft to resolve the service incident, save your files locally to your computer to prevent data loss.

Free Microsoft Office alternative

Try WPS Office for Seamless Document Management

While waiting for Microsoft 365 service issues to be resolved, you can continue your work without interruption using WPS Office. It is a free, lightweight, and highly compatible alternative to Microsoft Office that allows you to easily edit and save your files locally or to alternative cloud storage platforms.

1. Download WPS Office: Visit the official WPS Office website and download the free installation package for your operating system.
2. Install the Software: Run the installer and follow the on-screen instructions to complete the setup process in minutes.
3. Open and Edit Files Locally: Launch WPS Office, open your Microsoft Office documents, and save them locally to your hard drive until SharePoint services are restored.

Highly compatible with Microsoft Office formats (Word, Excel, PowerPoint).Free and lightweight, ensuring smooth operation on any device.Save files locally or to alternative cloud drives when SharePoint is down.Familiar user interface for a seamless transition without a learning curve.

Frequently Asked Questions

What does 'unhandled client error' mean in SharePoint?

An unhandled client error in SharePoint typically means your web browser encountered an unexpected issue communicating with the Microsoft 365 servers, often caused by a backend service outage or a server-side bug.

Why didn't clearing my browser cache fix the SharePoint upload error?

If the issue is caused by a tenant-specific configuration error or a global Microsoft 365 service incident (like MO801333), local troubleshooting steps like clearing the cache or resetting permissions will not resolve the backend server problem.

Can I upload files to SharePoint during a service incident?

During a service incident affecting file operations, uploads to SharePoint and OneDrive may be temporarily unavailable or highly unstable. You should save your work locally until your administrator confirms that Microsoft has resolved the health incident.

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