2

When I add an item to shopping cart, the checkout page is blank, only with the store logo.

And when I open system.log, it says

main.CRITICAL: Unable to unserialize value. [] []

What could be the reason for this error?

2
  • Is it a fresh installation? Dec 14, 2017 at 8:35
  • No, upgrade from 2.1
    – user9839
    Dec 14, 2017 at 10:56

1 Answer 1

0

Magento 2.2: Unable to unserialize value?

There was an answer. Change Json.php file as follows solved this issue.

 <?php
/**
 * Copyright © Magento, Inc. All rights reserved.
 * See COPYING.txt for license details.
 */
namespace Magento\Framework\Serialize\Serializer;

use Magento\Framework\Serialize\SerializerInterface;

/**
 * Serialize data to JSON, unserialize JSON encoded data
 *
 * @api
 * @since 100.2.0
 */
class Json implements SerializerInterface
{
    /**
     * {@inheritDoc}
     * @since 100.2.0
     */
    public function serialize($data)
    {
        $result = json_encode($data);
        if (false === $result) {
            throw new \InvalidArgumentException('Unable to serialize value.');
        }
        return $result;
    }

    /**
     * {@inheritDoc}
     * @since 100.2.0
     */
    public function unserialize($string)
{
    if($this->is_serialized($string))
    {
        $string = $this->serialize($string);
    }
    $result = json_decode($string, true);
    if (json_last_error() !== JSON_ERROR_NONE) {
         throw new \InvalidArgumentException('Unable to unserialize value.');

    }
    return $result;
}

function is_serialized($value, &$result = null)
{
    // Bit of a give away this one
    if (!is_string($value))
    {
        return false;
    }
    // Serialized false, return true. unserialize() returns false on an
    // invalid string or it could return false if the string is serialized
    // false, eliminate that possibility.
    if ($value === 'b:0;')
    {
        $result = false;
        return true;
    }
    $length = strlen($value);
    $end    = '';
    switch ($value[0])
    {
        case 's':
            if ($value[$length - 2] !== '"')
            {
                return false;
            }
        case 'b':
        case 'i':
        case 'd':
            // This looks odd but it is quicker than isset()ing
            $end .= ';';
        case 'a':
        case 'O':
            $end .= '}';
            if ($value[1] !== ':')
            {
                return false;
            }
            switch ($value[2])
            {
                case 0:
                case 1:
                case 2:
                case 3:
                case 4:
                case 5:
                case 6:
                case 7:
                case 8:
                case 9:
                    break;
                default:
                    return false;
            }
        case 'N':
            $end .= ';';
            if ($value[$length - 1] !== $end[0])
            {
                return false;
            }
            break;
        default:
            return false;
    }
    if (($result = @unserialize($value)) === false)
    {
        $result = null;
        return false;
    }
    return true;
}
}

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