PDF.js Message: Unexpected server response (0) while retrieving PDF – Error Solution Guide

Error Overview

The error message “PDF.js Message : Unexpected server response (0) while retrieving PDF” indicates that the PDF.js library encountered an unexpected response when attempting to retrieve a PDF file. This typically means that the server did not respond correctly, which can occur in various scenarios such as incorrect file paths, server issues, or improper configurations.

The error response code (0) suggests that the request may have failed silently, often due to network issues or because the file is not accessible. Addressing this issue requires understanding the underlying causes and implementing the correct solutions.

Common Causes

Several factors can lead to the “Unexpected server response (0)” error in PDF.js:

1. File Path Issues: The specified path to the PDF file may be incorrect or inaccessible.
2. Server Configuration: The server may not be set up to serve PDF files or may be misconfigured.
3. Network Connectivity: Issues with network connectivity can prevent the PDF file from being retrieved.
4. CORS Policy: Cross-Origin Resource Sharing (CORS) issues can block requests to PDF files hosted on a different domain.
5. Local File Access: The application may not have the appropriate permissions to access local files.
6. File Corruption: The PDF file itself may be corrupted or incorrectly formatted.
7. JavaScript Errors: Errors in the JavaScript code attempting to load the PDF can lead to this issue.
8. Browser Compatibility: Some browsers may not fully support PDF.js or have specific settings that block its functionality.

Solution Methods

To resolve the “PDF.js Message : Unexpected server response (0) while retrieving PDF” error, consider the following methods:

Method 1: Verify File Path

1. Ensure that the file path specified in your application is correct.
2. Check for typos or incorrect directory structures.
3. For web applications, confirm that the PDF file is available at the specified URL.

Method 2: Adjust Server Configuration

1. Verify that the server is configured to serve PDF files.
2. If using a web server, check the MIME types to ensure PDF files are properly recognized.
3. Restart the server after making any configuration changes.

Method 3: Handle CORS Issues

1. If accessing a PDF hosted on a different domain, ensure that the server’s CORS policy allows requests from your domain.
2. Modify the server configuration to include appropriate CORS headers, such as:
   http
Access-Control-Allow-Origin: *
3. Test the application again to see if the error persists.

Method 4: Local File Access Permissions (For UWP Apps)

1. If running a UWP (Universal Windows Platform) application, ensure that the application has permission to access local files.
2. Use the following code to access and convert the PDF file to Base64:
   “`csharp
   private async Task OpenAndConvert(string fileName)