Fatal error: Call to undefined function…class.cross-linker.php on line 17

Hi support – i received the following error:

Fatal error: Call to undefined function WordPress\Plugin\Encyclopedia\MB_Convert_Encoding() in /home/mysite/public_html/wp-content/plugins/encyclopedia-lexicon-glossary-wiki-dictionary/class.cross-linker.php on line 17

Any assistance would be appreciated muchly!

https://wordpress.org/plugins/encyclopedia-lexicon-glossary-wiki-dictionary/