Why Does File Manager Show 'Unknown' for Folder Sizes and How to Fix It

Many users of the File Manager plugin encounter a frustrating issue: when they try to check the size of a large number of files or folders, the plugin calculates for a while before ultimately displaying 'Unknown' instead of a file size. This guide will explain the common causes of this problem and provide steps you can take to resolve it.

Why This 'Unknown' Size Error Happens

Based on community reports and analysis, this behavior is typically not a bug in the plugin's code but a limitation imposed by your hosting environment. Calculating the size of numerous files is a resource-intensive process for a server. To prevent a single operation from consuming all available resources and crashing a site, servers have safety limits in place. The 'Unknown' result often appears when the File Manager plugin is stopped by one of these server-level restrictions before it can finish its calculation.

As one support response indicated, "It really depends upon your server because the file manager only provides you UI to show files and folders." The plugin acts as an interface; it can only work within the constraints set by the server it's running on.

Common Solutions to Try

1. Increase Your PHP Memory Limit

The most common culprit is a low PHP memory limit. The size calculation process needs enough allocated memory to complete. You can try increasing this limit.

• Via wp-config.php: Access your site's root directory via FTP or your host's file manager. Locate the wp-config.php file. Above the line that says /* That's all, stop editing! Happy publishing. */, add the following line:

  define( 'WP_MEMORY_LIMIT', '256M' );

  Save the file and retry the size calculation in File Manager.

2. Adjust Execution Time Limits

If the calculation is taking too long, the server might be halting the process. You can attempt to increase the maximum execution time.

• Via .htaccess (on Apache servers): Edit the .htaccess file in your root directory and add:

  php_value max_execution_time 300

• Via php.ini: If you have access to the php.ini file, change the max_execution_time directive.

3. Check for File Permission Issues

In one user's thread, they mentioned that "Volume root information was written that it was locked." This suggests that if the plugin does not have read permissions for all files and folders it is trying to scan, it will fail to calculate their size. Ensure your WordPress file and folder permissions are correctly set. Generally, directories should be 755 and files should be 644.

4. Rule Out Temporary Connectivity Issues

While less likely for a persistent problem, it's worth ensuring you have a stable internet connection, as a drop during the calculation could cause it to fail.

When to Consider Alternative Methods

If the above steps do not work, the constraints on your shared hosting environment may be too strict to overcome. In this case, you may need to calculate sizes using other methods:

• Your Hosting Control Panel: Most hosts (like cPanel) have their own file managers that can calculate sizes without the same PHP limitations.
• FTP/SFTP Client: Connect to your site with an FTP client like FileZilla. Selecting files and folders there will often show their total size.
• WordPress Plugins: Other plugins are designed specifically for diagnosing disk usage and may handle the process differently.

This issue highlights the complex interaction between a WordPress plugin and server configuration. By understanding these constraints, you can better troubleshoot and find a working solution for your needs.