Magento 2.3.0 error while changing dropdown attribute to visual swatches

Question

Fatal error: Uncaught Error: Call to a member function serialize() on null in /vendor/magento/module-swatches/Helper/Data.php:162

Stack trace: #0 /vendor/magento/module-swatches/Model/Plugin/EavAttribute.php(100):

Magento\Swatches\Helper\Data->assembleAdditionalDataEavAttribute(Object(Magento\Catalog\Model\ResourceModel\Eav\Attribute\Interceptor)) #1 

/vendor/magento/framework/Interception/Interceptor.php(121): 

Magento\Swatches\Model\Plugin\EavAttribute->beforeBeforeSave(Object(Magento\Catalog\Model\ResourceModel\Eav\Attribute\Interceptor)) 

#2 vendor/magento/framework/Interception/Interceptor.php(153): Magento\Catalog\Model\ResourceModel\Eav\Attribute\Interceptor->Magento\Framework\Interception\{closure}()

#3 /generated/code/Magento/Catalog/Model/ResourceModel/Eav/Attribute/Interceptor.php(26): Magento\Catalog\Model\ResourceModel\Eav\Attribute\Interceptor->___ in /vendor/magento/module-swatches/Helper/Data.php on line 162

please help and suggest possible solutions my magento version is 2.3.0

Answer 1

Finally i solved the error

$serializer variable was checked in constructor of the class vendor/magento/module-swatches/Helper/Data.php to be initialised with the help of ObjectManager if found uninitialised, but ternary operator in php ? : is not evaluating null property properly.

so i added

if(null == $this->serializer) { $this->serializer = ObjectManager::getInstance()->create(Json::class); }

before

$attribute->setData('additional_data', $this->serializer->serialize($additionalData)); 

Answer 2

Upgrade your magento with latest version of Magento 2 so error will automatically solved

php -d memory_limit=-1 bin/magento maintenance:enable

php -d memory_limit=-1 bin/magento deploy:mode:show

php -d memory_limit=-1 bin/magento deploy:mode:set developer

php -d memory_limit=-1 composer.phar require magento/product-community-edition=2.3.4 --no-update

php -d memory_limit=-1 composer.phar require --dev allure-framework/allure-phpunit:~1.2.0 friendsofphp/php-cs-fixer:~2.14.0 lusitanian/oauth:~0.8.10 magento/magento-coding-standard:~3.0.0 magento/magento2-functional-testing-framework:2.4.3 pdepend/pdepend:2.5.2 phpmd/phpmd:@stable phpunit/phpunit:~6.5.0 sebastian/phpcpd:~3.0.0 squizlabs/php_codesniffer:~3.4.0 --sort-packages --no-update

php -d memory_limit=-1 composer.phar remove --dev sjparkinson/static-review fabpot/php-cs-fixer --no-update

php -d memory_limit=-1 composer.phar update