Fatal Error: call_user_func_array() After Activating Linkilo

The error

When you activate Linkilo, WordPress shows:

Fatal error: Uncaught TypeError: call_user_func_array() expects ...

The cause

This error usually comes from a stricter PHP type check tripping on a legacy WordPress filter signature. It tends to show up on sites that have been mid-upgraded — PHP was bumped but a cached opcache or an older plugin (sometimes Linkilo itself, in very old versions) is still in memory.

The two reliable fixes are: switch to a modern, supported PHP version (8.1 or newer, ideally 8.2 / 8.3), or temporarily drop to a known-good older version while you isolate the conflict.

The fix

Switch your PHP version to 8.1, 8.2, or 8.3 — whichever your host supports. PHP 7.4 reached end-of-life in 2022 and shouldn't be used on a production site for security reasons, but if you need a quick rollback to keep the site running while you debug, 7.4 will work.

How to change PHP version

• cPanel hosts: Look for "MultiPHP Manager" or "PHP Selector" in cPanel
• SiteGround: Site Tools → Devs → PHP Manager
• Kinsta / WP Engine: Settings → Tools → PHP version
• Cloudways: Server Settings → Settings & Packages → PHP version

After changing PHP, reload your WordPress admin and reactivate Linkilo.

Still happening?

Run the plugin conflict detection guide — sometimes the fatal trace mentions our plugin but the root cause is a conflicting plugin. The detection guide isolates the culprit safely.