1. Problem Description
When uploading a .glb (3D Model) file to the WordPress Media Library, the system triggers the following error:
“This file cannot be processed by the web server.”
At first glance, it is easy to assume this is a server-side issue (Apache, Nginx, or OpenLiteSpeed) because the error message explicitly mentions the "web server."
2. Investigation Process
2.1 Browser Inspection (DevTools)
By opening F12 → Network tab while attempting the upload, we observed the following:
-
❌ No request was sent to the server.
-
❌ No error response was received from the server.
-
❌ The Console did not display any JavaScript errors.
Conclusion: The file is being blocked by WordPress’s internal logic before the request is even sent, rather than being rejected by the actual web server hardware or software.
3. The Root Cause
By default, WordPress restricts certain file types for security reasons. It only allows a predefined list of MIME types (such as .jpg, .png, .pdf, .mp4, etc.).
The .glb format (model/gltf-binary) is not on this default whitelist. Therefore:
-
WordPress blocks the file during the initial validation step.
-
It displays a generic "not supported" or processing error.
-
No communication with the server occurs.
Summary: This is strictly a WordPress configuration issue, not a web server failure.
4. Solution
4.1 Enable .glb Uploads in WordPress
To fix this, you need to add the .glb MIME type to the allowed list. Open your theme's functions file:
Path: wp-content/themes/your-theme/functions.php
Add the following code snippet:
PHP
add_filter('upload_mimes', function($mimes) {
// Add .glb support
$mimes['glb'] = 'model/gltf-binary';
return $mimes;
});
4.2 Save and Verify
-
Save the changes to
functions.php. -
Return to the WordPress Admin dashboard.
-
Navigate to Media → Add New.
-
Upload the .glb file again.
✅ Result: The file should now upload successfully without any error messages, and no web server adjustments are required.