Fix Cannot Upload DOCX or XLSX Files to SharePoint 2013
Question details
Users are unable to upload modern Office files (.docx, .xlsx) to SharePoint 2013 using a custom ASP.NET application in a production environment.
- Product
- SharePoint 2013 / ASP.NET
- Device & OS
- not provided
- Scenario
- Attempting to upload Microsoft Office documents to a SharePoint 2013 document library via a custom-built ASP.NET web application.
- Observed behavior
- Older file formats (.doc, .xls) upload successfully, but modern XML-based formats (.docx, .xlsx) fail to save or upload in the production environment.
Ensure you have access to both your development and production server configurations, as well as the error logs for your ASP.NET application. You will need administrative privileges on the IIS server hosting the application to check MIME types and folder permissions.
Verify IIS Configuration and MIME Types
Check the production IIS server to ensure it is configured to accept modern Office document MIME types and handle the upload size.
Because modern DOCX and XLSX files have different MIME types than older binary formats, the production IIS server might block them if the types are not explicitly allowed or if request filtering limits are too low.
Log into your production server and open the Internet Information Services (IIS) Manager from the Start menu.
Select your ASP.NET application's site in the left pane, and double-click the 'MIME Types' icon in the central Features View.
Scroll through the list to ensure '.docx' is mapped to 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' and '.xlsx' is mapped to 'application/vnd.openxmlformats-officedocument.spreadsheetml.sheet'. Add them if they are missing.
Return to the Features View, double-click 'Request Filtering', and ensure the maximum allowed content length is large enough for your Office documents.
Audit Application Code and Folder Permissions
Identify discrepancies between development and production environments regarding service account permissions and file validation.
Consult SharePoint Server Forums
Since this involves a custom ASP.NET application interacting with on-premises SharePoint 2013, specialized developer community support may be required to trace complex configuration bugs.
Edit DOCX and XLSX Files Effortlessly with WPS Office
While troubleshooting complex server and ASP.NET upload configurations, you can rely on WPS Office to open, edit, and save all your DOCX and XLSX files locally. It is a highly compatible and free alternative to Microsoft Office.
Frequently Asked Questions
Why do .doc files upload but .docx files fail in ASP.NET?
This usually happens because .docx files are essentially ZIP archives containing XML data. If your production server's request filtering, strict MIME type policies, or security software blocks ZIP/XML file structures, the upload will fail while older binary .doc files pass through unhindered.
How do I add DOCX MIME types to IIS?
Open IIS Manager, select your website, and double-click the MIME Types feature. Click 'Add' in the Actions pane, enter '.docx' as the file name extension, and type 'application/vnd.openxmlformats-officedocument.wordprocessingml.document' into the MIME type field.
Does SharePoint 2013 natively block XLSX or DOCX files?
No, SharePoint 2013 fully supports modern Office file formats natively. If uploads fail, the issue typically lies within the custom application's upload logic, IIS configuration, or a restrictive network proxy in the production environment.
How can I view detailed error messages for SharePoint 2013 uploads?
You can use the SharePoint ULS (Unified Logging Service) Viewer to monitor logs in real-time on your SharePoint server. When an upload fails, SharePoint generates a correlation ID. Filter the ULS logs by this correlation ID to trace the exact cause of the failure.
