How to diagnose the "500" error code in browser?

backend-category
(Niel Nijns) #1

I have a problem in my Magento 2.2.5 shop. I did the migration from magento 1.9.2.1

When I want to change the category from a product I get the next error: Unable to unserialize value.

The exception.log says

main.CRITICAL: Unable to unserialize value. {"exception":"[object] (InvalidArgumentException(code: 0): Unable to unserialize value. at /home/u53976p51115/domains/online-ledshop.be/public_html/vendor/magento/framework/Serialize/Serializer/Json.php:39)"}

I found a lot of solutions for this problem, Like change the Json.php file in vendor/magento/framework/Serialize/Serializer:

Change unserialize to

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;
}

And add this function:

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;
}

But when I do this I get a 500 error on my website.

Can someone help me please?

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(Dmitry Fedyuk) #2

The 500 error code means that the error’s output to browsers is disabled by the webserver’s settings.
You need to enable the error output to browsers or to a log file.

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