How to Fix SharePoint Online I/O Error When Uploading Files
Question details
Users encounter an "I/O error occurred" message that prevents them from uploading files, creating folders, or modifying documents in SharePoint Online.
- Product
- SharePoint Online
- Device & OS
- not provided
- Scenario
- Attempting to upload documents or manage files via modern web browsers in SharePoint Online document libraries.
- Observed behavior
- The operation fails completely with an "I/O error occurred" prompt. This issue persists across multiple browsers (Chrome, Edge, Firefox) and accounts, though File Explorer operations may still work.
Verify that your internet connection is stable and ensure you have the appropriate edit or upload permissions for the specific SharePoint document library.
Temporarily Disable or Configure Antivirus Software
Strict web-protection modules in antivirus software (like Bitdefender) can intercept and block SharePoint upload operations, causing I/O errors.
Many modern security programs scan web traffic in real-time. Sometimes, their aggressive filtering falsely identifies SharePoint's background upload scripts as a threat, cutting off the connection and triggering an I/O error.
Launch your antivirus software (e.g., Bitdefender) from the system tray and navigate to the Protection or Web Security settings.
Temporarily toggle off the web protection or HTTP scanning feature. Do not disable the entire firewall.
Return to your browser, refresh the SharePoint page, and attempt to upload the file again.
If the upload succeeds, re-enable your web protection immediately. Then, add the SharePoint URL (*.sharepoint.com) to the whitelist or exceptions list within your antivirus settings.
Switch to the Classic SharePoint Experience
Reverting to the legacy interface can bypass bugs or script conflicts present in the modern SharePoint or OneDrive experience.
Use File Explorer as a Workaround
Bypassing the web browser entirely by syncing the library to your desktop circumvents browser-based I/O errors.
Manage and Edit Your Documents Seamlessly with WPS Office
If persistent Microsoft SharePoint and Office online errors are slowing down your workflow, consider switching to WPS Office. It is a highly compatible, free, and lightweight alternative that allows you to create, edit, and save your documents without the heavy overhead of complex cloud configurations.
- 1. Download and Install: Get the free WPS Office installer from the official website and complete the quick installation.
- 2. Open Your Office Files: Drag and drop any existing Word, Excel, or PowerPoint files directly into WPS Office to start editing immediately.
- 3. Save to WPS Cloud: Enable WPS Cloud to securely back up your files and avoid browser-based upload errors altogether.
Frequently Asked Questions
Why am I getting an I/O error only in Chrome and Edge?
Modern antivirus software often utilizes specific web-protection modules that aggressively monitor Chromium-based browsers like Chrome and Edge. This monitoring can intercept and break the data streams used by SharePoint to upload files, resulting in an I/O error.
Will clearing my browser cache fix the SharePoint I/O error?
Generally, no. While unpinning tabs, restarting the browser, or clearing the cache might provide a brief temporary fix, it rarely solves the root cause. The issue is typically tied to security software interference or interface bugs in the modern SharePoint experience.
Does the I/O error affect downloading or reading existing files?
No, the "I/O error occurred" message almost exclusively affects write operations. This includes uploading new documents, modifying existing files, or creating new folders. Reading, viewing, or downloading files usually continues to function normally.
