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Resolving Common Sydney Theme Customizer Fatal Errors and Warnings

22 threads Sep 16, 2025 Theme → Sydney

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Many users of the Sydney WordPress theme encounter errors when trying to access the WordPress Customizer. These issues often manifest as fatal errors or warnings that prevent access to theme customization options. Based on community reports, this article explains the common causes and provides solutions to get your Customizer working again.

Common Error Messages

The errors typically appear in these forms:

  • Fatal errors referencing "Attempt to assign property on null" in files like woocommerce.php or component files
  • Warnings about "array_merge(): Expected parameter 1 to be an array, null given" in upsell.php
  • Warnings about "Invalid argument supplied for foreach()" in class_sydney_typography.php on line 128
  • General critical errors when accessing the Customizer

Why These Errors Occur

These errors typically happen due to:

  1. Theme/plugin conflicts - Particularly with page builders like Visual Composer
  2. Outdated theme versions - Using older Sydney versions that aren't compatible with current WordPress or PHP versions
  3. Child theme issues - Child themes that haven't been updated to match parent theme changes
  4. PHP version compatibility - Newer PHP versions (7.4+) are more strict about variable handling

Solutions to Try

1. Update Everything

Ensure you're running the latest version of the Sydney theme, WordPress, and all plugins. Many Customizer issues were addressed in newer Sydney releases.

2. Conflict Testing

Temporarily disable all plugins to see if the error disappears. If it does, reactivate plugins one by one to identify the conflicting plugin. Common conflicts occur with:

  • Page builders (Visual Composer, SiteOrigin Panels)
  • WooCommerce-related plugins
  • Child theme generator plugins

3. Child Theme Check

If using a child theme (like Bistro mentioned in several threads), ensure it's compatible with your current Sydney version. You may need to update your child theme's functions to match changes in the parent theme.

4. PHP Version Adjustment

If you're seeing warnings but not fatal errors, you might adjust your PHP error reporting settings. However, addressing the root cause is preferable to simply hiding warnings.

5. Manual File Check

For advanced users: Check the specific files mentioned in error messages (like upsell.php or component files) for proper array initialization before merge operations.

When to Seek Additional Help

If these solutions don't resolve your Customizer issues, you may want to:

  • Check the Sydney support forums for similar reports
  • Consult with a WordPress developer for theme-specific debugging
  • Consider temporarily switching to a default WordPress theme to confirm the issue is theme-specific

Remember to always backup your site before making significant changes, and test changes in a staging environment first when possible.

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