Fixing NGINX error: Cannot load CSS and JS files (4 solutions)

The Problem

When setting up a web server with NGINX, encountering issues with static content not loading properly is one problem many developers face. Specifically, NGINX can sometimes fail to serve CSS and JS files correctly, which can break the styling and functionality of web pages significantly. This issue might manifest itself with browser errors such as ‘404 Not Found’ when trying to load CSS or JavaScript, even though the files are physically present on the server. In this guide, we’ll explore several solutions to troubleshoot and fix the common problem where NGINX is not serving CSS and JS files.

Let’s Fix It

Solution 1: Check File Permissions and Ownership

Incorrect file permissions or ownership can prevent NGINX from reading and serving your CSS and JS files correctly.

1. Connect to your server using SSH.
2. Navigate to your website’s root directory using the cd command.
3. Use the command ls -l to check the permissions and ownership of your files and directories.
4. If the permissions are restrictive, you can use the chmod command to set the appropriate permissions. For example, executing chmod 644 *.css will set read and write permissions for the owner, and read-only permissions for other users, which is commonly required for web files.
5. To change ownership, if necessary, use the chown command, such as sudo chown www-data:www-data *.css, replacing www-data with the user and group that your web server runs under.

Note: While changing file permissions can fix access issues, be careful not to give overly permissive settings (such as 777) as this can pose a security risk. Always check your server’s requirements and set permissions accordingly.

Solution 2: Configure Correct NGINX Location Blocks

Sometimes, the issue can stem from misconfigured location blocks in the NGINX configuration file that don’t properly include paths to static content.

1. Open your NGINX configuration file (typically located at /etc/nginx/nginx.conf or within the /etc/nginx/conf.d/ or /etc/nginx/sites-available/ directories).
2. Within the server block, check for location blocks that are designated to serve static files. Ensure they are correctly set up to handle requests for CSS and JS files.
3. If these don’t exist or are misconfigured, add or modify them as follows:

location ~* \.(css|js)$ {
    root /path/to/your/static/files;
    try_files $uri =404;
    access_log off;
    expires max;
}

Note: It’s crucial to use the correct ‘root’ or ‘alias’ directives and ensure regular expressions in the location block are accurate. Misconfigured regular expressions can lead to files not being found. The above configuration assumes that requests for CSS and JS files can be globally caught and handled, which may not be suitable for all setups.

Solution 3: Check for Conflicting Server Blocks

Your server might have conflicting server blocks, or the server block dedicated to static files might not be correctly processed due to a conflicting catch-all server block.

1. Open your NGINX configuration file as mentioned in Solution 2.
2. Examine the file for multiple server blocks and identify if there’s a catch-all block that might be catching requests for static files.
3. If a conflict is identified, revise your server block(s) so that specific locations or patterns are used for static content, thereby avoiding the catch-all block processing these requests.

Without a correct server block for handling your CSS and JS files, requests may be processed incorrectly leading to errors or files not being found.

Solution 4: Clear Browser and Server Caches

Cached data may sometimes cause your browser to fail to load updated CSS and JS files. Cached server content can also have similar effects.

1. Clear your browser cache to eliminate the possibility that outdated or corrupted cache data is causing the issue. This can typically be done in your browser’s settings or by using keyboard shortcuts (e.g., CTRL + F5).
2. Restart NGINX to clear any server-side caches that might be affecting the loading of static content. You can usually restart NGINX with a command like sudo service nginx restart.

If you’re using content delivery networks (CDNs) or other caching systems, make sure to clear those caches as well.

Caveats and Final Notes

No single solution may apply to every NGINX CSS and JS file loading issue, as environments and configurations can differ vastly. Be sure to backup your configuration files before making changes, test your setup in a development environment, if possible, and apply changes carefully and incrementally to minimize downtime and other potential problems.