Why is it showing Serialization of Closure is Not Allowed Error in Laravel, and How to Fix It?

Introduction

While working with Laravel 5.5 (and later versions), many developers encounter the error:

Serialization of ‘Closure’ is not allowed

This error commonly appears when caching, queuing jobs, or storing objects that contain closures. Since Laravel relies on PHP’s serialization to store cached data or queue jobs, closures cannot be serialised—leading to this issue.

This article explains why this happens, explores real-world examples, and provides solutions and best practices.

Why the Error Happens

PHP’s serialization engine cannot handle closures (anonymous functions). When you attempt to cache or queue something that contains a closure, PHP throws this exception.

Laravel triggers this when you:
– Cache models/collections containing closures.
– Pass closures or objects containing closures into queued jobs.
– Cache views or configurations that internally include closures.

Example: Caching Eloquent with Relationships

A developer attempted to cache FAQs with related articles:

public static function cachedFaq()
 {
 	return Cache::remember('faq', 60 * 24 * 7, function () {
     	return self::with(['articles'])
         	->whereHas('parent', function ($query) {
             	$query->where('slug', 'faq');
         	})
         	->get();
 	});
 }

Error:

Serialization of ‘Closure’ is not allowed

The developer later discovered the actual cause: they had overridden the __construct() method in their Eloquent model, which introduced a closure into the object. Because PHP cannot serialise closures, Laravel failed when attempting to cache it.

Fix:

Remove or refactor the custom __construct() in the model. If you still need to prepare data for caching, convert it to an array:

return Cache::remember('faq', 60 * 24 * 7, function () {
 	return self::with(['articles'])
     	->whereHas('parent', fn($q) => $q->where('slug', 'faq'))
     	->get()
     	->toArray(); // ✅ Safe for caching
 });

Other Scenarios & Fixes

1. Queued Jobs Containing Request or Closures

Wrong: (passing whole $request into a job):

dispatch(new ProcessOrder($request));

Correct: (pass only needed fields):

dispatch(new ProcessOrder($request->only(['order_id', 'amount'])));

2. Caching Views

Wrong:

Cache::put('homepage', view('home'), 60);

Correct:

Cache::put('homepage', view('home')->render(), 60);

3. Caching Collections with Relationships

Wrong:

Cache::put('users', User::with('roles')->get(), 60);

Correct:

Cache::put('users', User::with('roles')->get()->toArray(), 60);

4. Closures Inside Config Files

Wrong (config/services.php):

'payment' => function() { return new PaymentService(); },

Correct:

'payment' => App\Services\PaymentService::class,

Conclusion

The “Serialization of ‘Closure’ is not allowed” error is common but easily preventable once you know the root cause. The fix is to avoid caching or queuing closures directly and instead pass plain data, arrays, or strings.

By following the above best practices, you’ll ensure your Laravel apps remain stable, cache-friendly, and queue-safe.

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