SharePoint Document Issues

How to Troubleshoot SharePoint Files That Become Corrupted After Upload

John Wilson Oct 10, 2026 869 views

Question details

Users need to identify why files uploaded to a SharePoint document library using PnP JS and SPFx appear corrupted and unreadable despite a successful upload status.

How to Troubleshoot SharePoint Files That Become Corrupted After Upload

Product: SharePoint, PnP JS, SPFx
Device & OS: not provided
Scenario: Uploading documents to a SharePoint library programmatically using custom PnP JS or SPFx solutions.
Observed behavior: The file upload process completes successfully without errors, but the resulting files in the SharePoint document library are corrupted and cannot be opened.

Before you start

Ensure you have Site Member or Owner permissions to view document libraries, access version history, and perform manual test uploads in the affected SharePoint site.

Solution 1Recommended

Compare File Properties and Isolate the Upload Method

Determine if the corruption is caused by the programmatic upload method, the specific document library, or automated background processes by comparing file metadata.

By comparing a manually uploaded file with the one uploaded via your SPFx script, you can determine if the binary payload is being altered during the API request or by a post-upload SharePoint automation.

Perform a manual upload test

Upload the same file manually through the SharePoint web interface. If the manually uploaded file opens correctly, the issue is isolated to your PnP JS/SPFx code.

Check version history and automation

Right-click the corrupted file in SharePoint and select 'Version History'. Look for subsequent automated modifications (like Power Automate flows or event receivers) that might be modifying the file properties immediately after upload.

Compare file sizes and hashes

Download both the manually uploaded file and the script-uploaded file. Check their exact byte sizes. A discrepancy usually indicates that the binary stream was improperly formatted or chunked during the PnP JS request.

Verify Content-Type and binary data format

Review your PnP JS API call. Ensure you are passing the file as a valid Blob or ArrayBuffer, and that the Content-Type header exactly matches the file's MIME type (e.g., application/pdf for PDFs).

Compare File Properties and Isolate the Upload Method

Data Encoding Warning: Avoid passing base64 strings directly as the file content payload unless you are specifically using a method designed for base64 decoding, as this is a common cause of file corruption.

Solution 2

Implement a Minimal PnP JS Upload Test

Use a stripped-down version of your upload code to rule out interference from complex application logic or custom metadata updates.

Free Microsoft Office alternative

Verify Your Downloaded SharePoint Documents with WPS Office

While troubleshooting SharePoint programmatic uploads, you need a reliable suite to quickly open, test, and verify the integrity of your Word, Excel, and PowerPoint files. WPS Office is a lightweight, fully compatible, and free alternative to Microsoft Office that makes diagnosing document corruption easy.

1. Download and install WPS Office: Visit the official WPS website to download the free suite and install it on your machine.
2. Download the SharePoint file: Download the potentially corrupted file from your SharePoint document library to your local storage.
3. Open and inspect the file: Open the downloaded file directly in WPS Office to verify if the text, structure, and formatting remain intact or if corruption errors are triggered.

Fully compatible with Microsoft Office formats (.docx, .xlsx, .pptx)Lightweight architecture allows for fast opening of large or complex filesFamiliar user interface ensures zero learning curve when testing documentsFree to use for everyday document viewing, editing, and troubleshooting

microsoft office alternative - wps office

Frequently Asked Questions

Why do files uploaded via PnP JS get corrupted in SharePoint?

This often occurs if the binary data is not passed correctly as a Blob or ArrayBuffer, or if the Content-Type header does not match the actual file format during the API request.

How can I tell if a SharePoint workflow is corrupting my uploaded files?

Check the version history of the document in the SharePoint library. If a new version is created automatically right after your upload by a system account or Power Automate flow, that automation may be altering and corrupting the file's structure.

Does file size affect SPFx uploads to SharePoint?

Yes. PnP JS has different API methods for small files and large files (chunked uploads). Using a standard, single-request upload method for files larger than 10MB can lead to timeouts, incomplete data transfers, and subsequent file corruption.