Troubleshooting the 'Scan process ended after forking' Error in Wordfence

If you're seeing the "Scan process ended after forking" error in your Wordfence Security dashboard, you're not alone. This is a common issue that can prevent the plugin's malware scanner from running correctly. This guide will explain why this error occurs and walk you through the most effective troubleshooting steps to resolve it.

What Does This Error Mean?

The error occurs during the initial "forking" stage of a Wordfence scan. Forking is a technical process where the main scan creates a separate, independent process to handle the intensive work of checking your files. If this child process fails to start or communicate back to the main plugin, the scan terminates with this error message. This is often caused by server configuration restrictions, resource limits, or conflicts.

Common Solutions to Fix the Forking Error

Based on community reports and successful resolutions, the following steps are the most effective ways to address this problem. Work through them in order.

1. Adjust Basic Scan Performance Settings

Start by optimizing the scan's resource usage within the Wordfence interface.

• Navigate to Wordfence > Scan > Scan Options and Scheduling.
• In the Performance Options section, set the "Maximum execution time for each scan stage" to a lower value, such as 20.
• In the Advanced Scan Options section, enable the option "Use only IPv4 to start scans".
• Click "Save Changes" and attempt to run a new scan.

2. Increase PHP Memory Limits

Insufficient memory is a frequent cause, especially on resource-constrained hosting plans. The scans in the sample threads showed memory usage around 236MB.

• Edit your site's wp-config.php file and add or modify the following line to increase the WordPress memory limit:
  define('WP_MEMORY_LIMIT', '256M'); or define('WP_MEMORY_LIMIT', '512M');
• Ensure your hosting provider's PHP memory_limit setting (visible in your hosting control panel or on the Wordfence > Tools > Diagnostics page) is equal to or higher than the value you set for WordPress.

3. Configure Debugging and Remote Start Settings

Certain debugging features can interfere with the forking process.

• Go to Wordfence > Tools > Diagnostics.
• Scroll down to the Debugging Options section.
• Enable "Enable debugging mode".
• Ensure "Start all scans remotely" is disabled (unchecked).
• Click "Save Changes" and try another scan.

4. Check for Server-Level Restrictions

Server security modules or configurations can block the forking process.

• ModSecurity: This web application firewall (WAF) can sometimes false-positive and block the scan request. You may need to contact your hosting provider and ask them to check their ModSecurity audit log for any rules that were triggered (e.g., a 403 Forbidden error) during a Wordfence scan attempt.
• Disabled Functions: Some hosts disable core PHP functions like curl_exec for security. If the cURL function is disabled on your server, it will prevent Wordfence from communicating properly. You would need to request that your host enable it.
• PHP Version: While Wordfence is compatible with PHP 7.4, it is an outdated and unsupported version. Upgrading to a newer, supported PHP version (e.g., 8.1 or 8.2) can resolve many underlying compatibility issues.

5. Advanced Database Troubleshooting

In rare cases, corruption in the plugin's database tables can cause this error.

• If you have a database caching plugin or object caching enabled, try clearing that cache entirely.
• Using a tool like phpMyAdmin, you can attempt to "Repair" the wfConfig table in your WordPress database.
• As a last resort, a complete reinstall of Wordfence can reset its tables. Be sure to export your settings first from Wordfence > Tools > Import/Export Options so you can restore them afterward.

When to Seek Further Help

If you have tried all the steps above and the error persists, the issue may be highly specific to your server environment. To get more targeted help from the community, you can provide additional diagnostic information. From the Wordfence > Tools > Diagnostics page, you can use the "Send Report by Email" button to generate a detailed report of your site's configuration. You can then share relevant snippets of this data (while redacting sensitive information) when asking for help on community forums.

Persistent forking errors can be frustrating, but they are almost always solvable by adjusting server resources or configuration. Methodically working through these steps will most likely get your scans running smoothly again.