Magento 2.2: Unable to unserialize value?

I was able to resolve this issue by Flushing my Redis Cache from the CLI

redis-cli flushall 

I hope this helps future users.

The problem is in /vendor/magento/framework/Serialize/Serializer/Json.php there is a function unserialize($string) which gives you a syntax error if string is serialized (not json but php serialization).

There is a workaround - you can check if string is serialized (vs json-encoded) and then use serialize($string). 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 function to check if string is serialized:

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; } 

After save fe. category without problem, You can restore class to default and there wont be such problem in future.

In my case, I patched as follows to unserialize a serialized string: File: /vendor/magento/framework/Serialize/Serializer/Json.php

Find:

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; } 

replace by:

public function unserialize($string) { $result = json_decode($string, true); if (json_last_error() !== JSON_ERROR_NONE) { if(false !== @unserialize($string)){ return unserialize($string); } throw new \InvalidArgumentException('Unable to unserialize value.'); } return $result; } 

Do not edit core files for solution. Override following way Just put following line in di.xml inside etc directory

<preference for="Magento\Framework\Serialize\Serializer\Json" type="Namespace\ModuleName\Serialize\Serializer\Json" /> 

And inside Namespace\ModuleName\Serialize\Serializer Directory: file Json.php

<?php namespace Namespace\ModuleName\Serialize\Serializer; class Json extends \Magento\Framework\Serialize\Serializer\Json { /** * {@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; } } 

Works perfectly

After flushing Redis the issue has sorted. Thank you Craig for the solution.

I'm using port 6379 for cache, so I run command :

redis-cli -p 6379 flushall 

It's mostly related with Redis cache, so try to flush out this with simple command in your SSH

redis-cli flushall

For what it is worth, the above approach did not work for me and I found that an empty string was being passed to the unserialize function. Doing a check and returning an empty array solved my issue. It's a hack, but was able to move on.

public function unserialize($string) { if(empty($string)){ return []; } 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; } 

Sameers' answer above worked for me although i had to use different code in the block.

public function serialize($data) { $result = json_encode($data); if (false === $result) { throw new \InvalidArgumentException('Unable to serialize 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) { $result = null; return false; } return true; } /** * {@inheritDoc} */ public function unserialize($string) { if($this->is_serialized($string)) { $result = $this->serialize($string); } $result = json_decode($string, true); return $result; } 

I personally found this issue reared it's head running the command:

php bin/magento setup:upgrade 

After a migration. I found out that I was missing the "crypt" hash key in src/app/etc/env.php:

<?php return [ 'backend' => [ 'frontName' => 'admin' ], 'crypt' => [ 'key' => 'xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx' ], ... 

Ensure this is not empty and preferably matches your projects' other environments!

I was getting the error in a CMS page in front end.

It was the Magento widget code in the CMS Page Content that was causing problem(which I copied from another source). I deleted the widget code and inserted the same widget using the Insert Widget button in the CMS Page edit screen and it worked.

The above process formatted the widget code differently and it made the error go away.

ROOT directory 1. public_html/vendor/magento/framework/Serialize/Serializer/Json.php

Download JSON.php https://gist.github.com/manojind/9f18bbecaeb3e2bbfb056a634ade62a2

2. Just replace below function (unserialize) and add new function OR just download the attached file and replace with default

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; } 

3. Add new function :

function is_serialized($value, &$result = null) { if (!is_string($value)) { return false; } if ($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': $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; } 

I found out that whole serialized data cannot be fit into a database MySQL table column with TEXT data type.
I just found the column flag_data value of system_config_snapshot line is trimmed.

I had to change it to MEDIUMTEXT for this column flag.flag_data.

Was same error. When tried to update database(ver 2.2.6) with fresh code (ver 2.3.2).

For fix - runned

composer update 

This is not the best way to run sql directly but i did that for save my time. Just run this query

ALTER TABLE flag MODIFY flag_data LONGTEXT; UPDATE flag SET flag_data = '{"system":"","scopes":"","themes":""}' WHERE flag_code = 'config_hash'; UPDATE flag SET flag_data = '{}' WHERE flag_code = 'system_config_snapshot'; 

If you are on 2.3.0 or greater you will want to use the solution provided by MageLearner. The older way with case statements is obsolete. If you don't use MageLearner's solution on 2.3.0 or greater; you will hit all sorts of problems with viewing order data and configurable products.

I'm on Magento 2.3.3 with Mailchimp installed. When I updated my Mailchimp to the latest version the error disappeared: https://github.com/mailchimp/mc-magento2/releases/tag/102.3.41 You can also see in there release notes that they fix this issue.

In my case, I used Magento\Framework\Serialize\Serializer\Json instead of Magento\Framework\Serialize\Serializer\Serialize to decode or encode JSON object and then the error were disappeared.