Hello Aveeva,
Magento 2 serializes data using the serialize() method. However, some users faced an error like "unable to unserialize value" while working with system configuration. It's because of the Json class or the \Magento\Framework\Serialize\Serializer\Json class.
The error can appear when the file vendor/magento/framework/Serialize/Serializer/Json.php is causing the issue. The function unserialize($string) is used to check if the string is already serialized or not.
In order to resolve the error, you must follow the steps below,
- Firstly, open the below file,
vendor/magento/framework/Serialize/Serializer/Json.php
- Now, locate the following function in the file,
public function unserialize($string)
{
$result = json_decode($string, true);
if (json_last_error() !== JSON_ERROR_NONE) {
throw new \InvalidArgumentException('Unable to unserialize value.');
}
return $result;
}
- Then, modify the function by adding the below code,
public function unserialize($string)
{
/* Added this code to resolve the issue */
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 $result;
}
- Lastly, add the is_serialized() function on the below file at the end,
vendor/magento/framework/Serialize/Serializer/Json.php
function is_serialized($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;
}
Thus, with the help of json, you can unserialize the previous values and serialize them back. I hope the above method helps you to fix the syntax error: unable to unserialize value in Magento 2.
--------------------------
Regards,
Rex M
VPS Hosting | Magento Hosting
