eXtplorer - PHP-based File Manager

Just after recent update on my website for latest joomla 2.5.17 and eXtplorer 2.1.15 (everything was working fine before) every time I'm trying to edit file getting error:

Chrome:
JSON Decode Error: Cannot call method 'destroy' of undefined

Internet Explorer:
JSON Decode Error: Unable to get value of the property 'destroy': object is null or undefined

or when trying to download / chmod - I'm getting message : * This item doesn\'t exist..*

Any suggestions, please?