[SOLVED] Error decoding JSON data: Control character error, possibly incorrectly encoded.
If a Joomla website has many active languages, for example over than ten, as you can see in this screenshot, then there are many possibilities to see an error like this "An error has occurred. Error decoding JSON data: Control character error, possibly incorrectly encoded" after saving the plugin parameters.
This error means that you don't have enough space in the MySql column "params", of the table "#__extensions", to save all the required parameters that the Cookies Policy Notification Bar needs, and the json data breaks during saving the data.
1. First of all you have to permanently delete the folder "/plugins/system/cookiespolicynotificationbar/".
2. Then, uninstall the plugin. Extensions > Mange > System - Web357 Cookies Policy Notification Bar (Check the box and click on the uninstall button at top left).
3. Navigate to the phpMyAdmin, via cPanel or Plesk, find the table "#__extensions", and c hange the type of the column "params" from "TEXT" to "LONGTEXT", as you can see in the screenshot below.
4. Install again the Joomla! plugin, navigate to the "Cookies Policy Notification Bar" parameters, and now you can save all the parameters without any error.