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Troubleshooting Code Snippets and PHP 8 Compatibility Issues

23 threads Sep 16, 2025 Plugin → Code snippets

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Upgrading to a newer version of PHP, such as PHP 8.0, 8.1, 8.2, or 8.3, is a great way to improve your site's performance and security. However, many Code Snippets users report encountering a critical error or a blank white screen after making the switch. This guide will help you understand why this happens and how to resolve it.

Why Does This Happen?

Based on extensive community reports, the core Code Snippets plugin is developed and tested on modern PHP versions. The vast majority of post-upgrade failures are not caused by the plugin itself but by the code within individual snippets. Newer PHP versions introduce stricter error handling and deprecate older functions, which can cause previously working code to fail.

The most common culprits found in user snippets are:

  • Deprecated Functions: The create_function() function, which is often used in older snippets, was completely removed in PHP 8.0 and will cause a fatal error.
  • Undefined Constants/Variables: PHP 8+ is less forgiving of code that uses undefined constants, often mistyped strings without quotes (e.g., business_name instead of 'business_name').
  • Type Errors: Stricter type checking in PHP 8.2+ can cause errors if a function expects a boolean (true/false) but receives a null value.

How to Troubleshoot and Fix the Problem

Step 1: Regain Access to Your Site with Safe Mode

If your site is showing a critical error or white screen, your first step is to regain access. The Code Snippets plugin includes a built-in Safe Mode for this exact scenario.

  1. Add ?safe_mode=1 to the end of your WordPress admin URL (e.g., yoursite.com/wp-admin/?safe_mode=1).
  2. Log in. Safe Mode will temporarily deactivate all your snippets, allowing you to access the plugins page and the Code Snippets management area.

Step 2: Identify the Problematic Snippet

Once you have access, you need to find which snippet is causing the crash.

  1. Ensure all your snippets are deactivated.
  2. Switch your site back to the new PHP version (e.g., PHP 8.2). If the site works, you've confirmed the problem is a snippet, not the plugin.
  3. Re-activate your snippets one by one, checking your site frontend and backend after activating each one. The one that causes the error to return is the culprit.
  4. Alternatively, check your server's PHP error logs. The fatal error message will usually point directly to the problematic function or constant in your snippet code.

Step 3: Fix the Snippet Code

Once you've identified the problematic snippet, you will likely need to update its code to be compatible with modern PHP standards. Here are the fixes for the most common issues:

Issue: Uncaught Error: Call to undefined function create_function()
Fix: Replace the deprecated create_function() with an anonymous function.
Old Code:
add_filter( 'get_search_form', create_function( '$a', "return null;" ) );
New, PHP 8-Compatible Code:
add_filter( 'get_search_form', function( $a ) { return null; } );

Issue: Uncaught Error: Undefined constant "constant_name"
Fix: Ensure all strings are wrapped in quotes.
Erroneous Code:
return array( 'width' => width, 'height' => height );
Fixed Code:
return array( 'width' => 'width', 'height' => 'height' );

Conclusion

Encountering an error after a PHP upgrade can be alarming, but it is almost always solvable. The issue almost invariably lies with the code in a specific snippet, not the Code Snippets plugin itself. By methodically using Safe Mode and reactivating snippets one by one, you can identify and update the non-compliant code, allowing you to enjoy the benefits of newer PHP versions without losing any functionality.

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