facing error when i upgrade magento 2.4.4 with php 8.1, mysql 8.0 and using composer upgrade getting error below

Fatal error: During inheritance of Countable: Uncaught Exception: Deprecated Functionality: Return type of Composer\Repository\ArrayRepository::count() should either be compatible with Countable::count(): int, or the #[\ReturnTypeWillChange] attribute should be used to temporarily suppress the notice in vendor/composer/composer/src/Composer/Repository/ArrayRepository.php on line 277 in n vendor/magento/framework/App/ErrorHandler.php:61

3 Answers 3


I think the problem may be that you've upgraded to PHP 8.1 before you've upgraded your composer packages. Have a read of this github issue, seems others had the same issue:

From this thread, it seems like the accepted approach is:

  • STAY IN PHP 7.4
  • composer require magento/composer-root-update-plugin ~2.0 --no-update
  • composer update
  • rm -rf var/cache/* ; rm -rf var/page_cache/* ; rm -rf generated/code/*; - bin/magento setup:upgrade
  • composer require-commerce magento/product-community-edition 2.4.4 --no-update
  • composer update
  • rm -rf var/cache/* ; rm -rf var/page_cache/* ; rm -rf generated/code/*;
  • bin/magento setup:upgrade

Of course, if you're a developer and owner of your codebase - I'd advise you first check for any overwritten files that may need updating as part of the upgrade with https://github.com/AmpersandHQ/ampersand-magento2-upgrade-patch-helper

  • It works, just a comment: the second 'composer update' needs to run with php8.1. Commented Apr 14, 2023 at 11:44

Thanks Liam Toohey, But not worked. I found another solution. That is worked

As of PHP 8.1, you have to fix the return type of the functions count(). We need to modify 2 files.

Change public function count() to public function count(): int

Goto => \vendor\composer\composer\src\Composer\Repository\ArrayRepository.php (line 277)

public function count(): int
    if (null === $this->packages) {
    return count($this->packages);

Temporary solution:


// public function count()
   public function count(): int

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