Blazor Server APP Deployed on NGINX via Reverse Proxy Returns 404 Not Found for blazor.server.js

When deploying a Blazor Server app on NGINX using a reverse proxy, encountering a "404 Not Found" error for blazor.server.js usually indicates that NGINX is unable to locate the required JavaScript file. This issue can occur due to incorrect NGINX configuration or file path settings. To resolve this problem, consider the following steps:

1. Ensure Correct NGINX Configuration: Verify that your NGINX configuration is correct and includes appropriate directives for the reverse proxy. Here's an example of an NGINX configuration for a Blazor Server app:

   perlCopy code
   server {
       listen 80;
       server_name example.com;
   
       location / {
           proxy_pass http://localhost:5000;   # Adjust the port to match your Blazor Server app's port
           proxy_http_version 1.1;
           proxy_set_header Upgrade $http_upgrade;
           proxy_set_header Connection keep-alive;
           proxy_set_header Host $host;
           proxy_cache_bypass $http_upgrade;
       }
   }
   

   Replace example.com with your actual domain name and adjust the proxy_pass URL to match the URL of your Blazor Server app. Ensure that the proxy_pass URL includes the correct scheme (http or https) and port number.

2. Verify Blazor Server App's Port: Ensure that your Blazor Server app is running on the specified port (e.g., port 5000 in the example above). If the app is running on a different port, update the proxy_pass URL accordingly.

3. Check File Path Settings: Make sure that the Blazor Server app's files, including blazor.server.js, are located in the correct directory accessible by NGINX. By default, blazor.server.js is served by the Blazor Server app itself. It should be located under the /wwwroot/_framework directory of your app.

4. Check for File Permissions: Ensure that the NGINX user has appropriate permissions to access the Blazor Server app's files, including blazor.server.js.

5. Clear NGINX Cache (If Enabled): If NGINX cache is enabled, try clearing the cache and restarting NGINX to ensure that any potential caching issues are resolved.

6. Check NGINX Error Logs: Review the NGINX error logs for any relevant error messages that could shed light on the "404 Not Found" issue.

7. Restart NGINX: After making changes to the NGINX configuration, don't forget to restart NGINX to apply the changes.

By carefully reviewing your NGINX configuration and verifying the file paths and permissions, you should be able to resolve the "404 Not Found" error for blazor.server.js and successfully serve your Blazor Server app through the NGINX reverse proxy.