Fixing 404, 403, 406, and 500 Errors When Saving Breadcrumb NavXT Settings

Are you encountering a sudden 404, 403, 406, or 500 Internal Server Error immediately after clicking the "Save Changes" button in your Breadcrumb NavXT settings? You're not alone. This is a common and frustrating issue reported by many users. The good news is that it's almost never a problem with the plugin's code itself, but rather a security measure on your server being triggered.

Why This Happens: The Root Cause

Based on extensive community reports, the overwhelming majority of these errors are caused by a Web Application Firewall (WAF) with overly aggressive or sensitive rules. The most common culprit is the ModSecurity module for Apache servers.

When you save your Breadcrumb NavXT settings, the plugin sends data that includes HTML and template code (like <meta> tags) to the server. Certain ModSecurity rules are designed to prevent protocol attacks (like HTTP Response Splitting) by blocking requests that contain specific patterns of HTML. The plugin's template code can sometimes match these patterns, causing the firewall to block the request and return an error instead of saving your settings.

How to Troubleshoot and Resolve the Issue

Step 1: Confirm the Culprit

Check your server's error logs. This is the most crucial step for diagnosis. The logs will often explicitly mention "ModSecurity" and provide a specific rule ID (e.g., [id "921130"]) that was triggered. This confirms the issue is server-side security and not a bug in WordPress or the plugin.

Step 2: Work With Your Web Host (Recommended Solution)

Since ModSecurity is a server-level configuration, most users will need to contact their web hosting provider's support team. You can provide them with the error log entry showing the ModSecurity rule that was triggered. They can often:

• Whitelist the specific rule for your website.
• Adjust the rule set to be more compatible with WordPress.
• Disable ModSecurity for your account (a less ideal but effective temporary fix).

Step 3: Check Other Security Plugins

As seen in one thread, the WordFence plugin can also sometimes interpret the save action as unsafe and block it with a 403 error. If you use WordFence or a similar security plugin, try temporarily disabling it and then attempt to save your Breadcrumb NavXT settings again. If it works, you will need to adjust your security plugin's settings or whitelist the action.

Step 4: For the "Cannot Delete Plugin" Issue

A separate but related issue prevents some users from deleting the plugin. The Breadcrumb NavXT team has acknowledged this is a bug and is working on a fix for a future release. The current workaround is to deactivate the plugin and then delete its files manually via FTP or your hosting file manager. The directory is typically located at /wp-content/plugins/breadcrumb-navxt/.

Summary

If you cannot save settings and get an error, your first action should be to check your server error logs for ModSecurity entries. Your next step is to contact your web host to adjust the firewall rules. This approach has successfully resolved the issue for countless users.