Magento 2 : Deprecated Functionality: Function ReflectionType::__toString() is deprecated

Question

When I try to execute bin/Magento setup:install from command line I get an exception as "Deprecated Functionality: Function ReflectionType::__toString() is deprecated". It gives the same error for my previous Magento instance when I do

bin/magento setup:upgrade

It was running all good a few days earlier.

Any solution for this?

Note: I am using PHP 7.4 on my machine and installed Magento 2.3

Thank You

Answer 1

Magento 2.3 is not compatible with Php 7.4, So there are two possible solutions:

1. Downgrade you Php version to 7.3 - Recommended
2. If it is not possible for you to downgrade php version, you need to perform few changes in core files. This is a work around until Magento get compatible version for Php 7.4. When installing on my end I had faced few issues, this is what I did.

Change 1:

File: vendor/zendframework/zend-code/src/Reflection/ParameterReflection.php

In function detectType() replace line return (string) $type; with return $type->getName();

Change 2:

Error: Deprecated Functionality: implode(): Passing glue string after array is deprecated

File: vendor/magento/framework/DB/Sql/UnionExpression.php

In function __toString() replace line $sql = implode($parts, $this->type); with $sql = implode($this->type,$parts);

Change 3:

File: vendor/magento/framework/App/AreaList.php

In function getCodeByFrontName() replace line if ($areaInfo['frontName'] == $frontName) with if (isset($areaInfo) && $areaInfo['frontName'] == $frontName)

Hope you will find it helpfull.

Thanks

Answer 2

One more change in message queue batch consumer file if needed

Deprecated Functionality: Unparenthesized a ? b : c ?: d is deprecated. Use either (a ? b : c) ?: d or a ? b : (c ?: d) in /
vendor/magento/framework-message-queue/BatchConsumer.php on line 154

Before:

$count = $maxNumberOfMessages
            ? $maxNumberOfMessages
            : $this->configuration->getMaxMessages() ?: 1;
        

After:

$count = ($maxNumberOfMessages
            ? $maxNumberOfMessages
            : $this->configuration->getMaxMessages()) ?: 1;

Ref. https://github.com/magento/magento2/blob/2.4/lib/internal/Magento/Framework/MessageQueue/BatchConsumer.php#L154

Answer 3

I had Got same ""Deprecated Functionality: Function ReflectionType::__toString() is deprecated" when i was installing magento2.3.6 on php7.4.

I had did some more changes in magento vendor module as above @abdul defined for work in staging server.

File 1: vendor/laminas/laminas-code/src/Reflection/ParameterReflection.php file

Change detectType function if condition where return type is converted in string. I had remove string

if (method_exists($this, 'getType')
        && ($type = $this->getType())
        && $type->isBuiltin()
    ) {
        return $type->getName();
    }

File 2: vendor/magento/module-catalog/Model/Category/Attribute/Backend/Sortby.php

i was changed beforeSave function. updated ternary operator there.

find in beforeSave function.

$attributeValue = is_array($data) ? reset($data) :
                (!empty($data)) ? $data : null;

To

$attributeValue = (is_array($data) ? reset($data) :
                (!empty($data))) ? $data : null;

File 3: vendor/magento/framework/App/AreaList.php

change in public function getCodeByFrontName($frontName) function

find

if ($areaInfo['frontName'] === $frontName) {

And Replace it with

if (isset($areaInfo) && $areaInfo['frontName'] == $frontName) {

As above @abdul describe.

After i had execute successfully "setup:upgrade" and "Static-content:deploy -f" command.