Learn how to fix the “Unable to Unserialize Value” error in Magento 2. Our Magento Support team is here to assist you with any questions or concerns you may have.
“Unable to Unserialize Value” Error in Magento 2
The `Unable to unserialize value` error in Magento 2 is a commonly seen error. It typically appears due to issues with data serialization. This occurs when Magento attempts to convert a serialized string back into its original form but fails due to format inconsistencies or corrupted data.
In this blog, we will examine the causes of this error, its effects, and effective ways to resolve it.
Here is how the error message usually appears:
Exception #0 (InvalidArgumentException): Unable to unserialize value.
This indicates that Magento encountered a problem while attempting to unserialize a string. The root cause is often that the string is either improperly formatted or already serialized.
This error is just one of many serialization-related challenges Magento developers face. For instance, similar issues include the infamous “Invalid block type” error or transaction problems like the “Rolled back transaction has not been completed correctly” error.
An Overview:
Impacts of the Error
The effects of this error can disrupt different parts of our Magento store:
- We may be unable to save configuration settings.
- Adding or editing products may trigger the error.
- The site may slow down or crash if the issue isn’t addressed.
- Improper serialization may lead to corrupted configuration or product data.
- In severe cases, we may even encounter blank pages with no error messages, making debugging harder.
Common Causes and How to Fix Them
1. Incorrect Serialization Format
A mismatch between JSON and PHP serialization methods.
Click here for the Solution.
- First, verify whether the data originates from configuration files, APIs, or database fields.
- Ensure Consistent Serialization:
$data = json_encode($yourArray); $result = json_decode($data, true);Copy Code - Also, ensure that the changes resolve the issue across the entire application.
2. Corrupted Data
Data corruption during migrations or updates.
Click here for the Solution.
- First, back up the database.
- Use SQL queries to check tables like `core_config_data` for anomalies.
- Delete or fix corrupted entries:
DELETE FROM core_config_data WHERE <condition>;Copy Code - Then, run CLI tools:
php bin/magento setup:db-schema:upgrade php bin/magento setup:db-data:upgradeCopy Code
Corruption during upgrades can often lead to broader issues such as blank pages or error logs with no specific stack trace, so it’s crucial to act quickly.
3. Misconfigured Backend Models
Some configuration fields may use an incompatible backend model.
Click here for the Solution.
- First, check for usage of `Magento\Config\Model\Config\Backend\Serialized\ArraySerialized`.
- Then, update misconfigured entries in `core_config_data`.
UPDATE core_config_data SET value = '<correct_value>' WHERE path = '<config_path>';Copy Code - Clear the cache and test functionality.
4. Outdated Magento Version
Compatibility issues in outdated Magento versions.
Click here for the Solution.
- First, check the Magento version.
- Then, review Magento’s release notes for bug fixes.
- Now, update using Composer:
composer update php bin/magento setup:upgradeCopy Code
5. Redis Cache Issues
Stale entries in the Redis cache.
Click here for the Solution.
6. Custom Module Conflicts
Custom modules are overriding core functionality incorrectly.
Click here for the Solution.
- Disable custom modules temporarily:
php bin/magento module:disable Vendor_ModuleNameCopy Code - Then, re-enable modules one at a time to identify the culprit.
- Review the serialization logic in custom code for compliance.
7. Errors in Configuration Files
Invalid syntax in XML configuration files.
Click here for the Solution.
- Check XML files in `app/etc` and `app/code/Vendor/Module/etc`.
- We can use an XML validator to spot errors.
- After fixing, redeploy:
php bin/magento setup:di:compile php bin/magento cache:cleanCopy Code
8. PHP Version Compatibility
Running Magento on an unsupported PHP version.
Click here for the Solution.
- First, check the PHP version:
php -vCopy Code - Match the version with Magento’s compatibility matrix.
- Upgrade/downgrade PHP as needed.
- Restart the web server and verify functionality.
Prevention Tips
- Always back up files and databases before updates or changes.
- Keep Magento and its extensions updated.
- Test changes in a safe environment before going live.
- Especially for custom modules and third-party integrations.
- Use tools to detect issues early before they become critical. This applies not only to Magento errors but also to broader infrastructure issues, such as HAProxy backend failures, which can indirectly impact your eCommerce store’s uptime and performance.
[Need assistance with a different issue? Our team is available 24/7.]
Conclusion
In brief, our Support Experts demonstrated how to fix the “Unable to Unserialize Value” error in Magento 2.
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