Error generated by includes/function.php at unserialize

Hello,

For some reason it seems that the wpdiscuz plugin is creating an error in our system when it tries to unserialize the json from the database.

unserialize(): Error at offset 283 of 885 bytes [website url]\wp-includes\functions.php (line: 330) URL: /wp-admin/admin-ajax.php File: /wp-admin/admin-ajax.php

I don’t know why this is happening and when I go to jsonlint.com and valodate the json that wordpress tries to deserialize I get the following error message

Error: Parse error on line 1:
s: 3938: “a:100:{s:1
^
Expecting ‘STRING’, ‘NUMBER’, ‘NULL’, ‘TRUE’, ‘FALSE’, ‘{‘, ‘[‘, got ‘undefined’

I hope you guys can help me figure out why this is happening.
It is causing an overload of error messages to be logged in our database.

Thanks for the support.

Kind regards