Magento 2.2.0 and higher introduced some major change in the terms of serialization. It switched to json serialization instead of regular.
If you encounter a White screen in the configuration of the HrefLang extension or you get the error message: "Unable to serialize value" on Magento 2.2.x, please check the following solutions:
1) Update to version 1.0.5 or higher.
If you are running a version lower than 1.0.5 of the module you need to update, as from version 1.0.5 Magento 2.2.x is supported. You can download this version from your customer account dashboard.
2) If you are running on version 1.0.5 or higher and the problem still exists.
The module should automatically convert the data on the first load in the configuration.
If this does not work, follow these steps:
- Login to you Magento 2 database using phpmyadmin or other db tool.
- Open core_condig_data table.
- Remove row where path is "magmodules_alternate/targeting/stores".
After executing this database action login to your Magento admin flush cache and re-enter the correct targeting settings.