Fatal error: Call to undefined function mb_strtolower()

The new Tooltip Glossary since version 2.6.0 requires the mbstring PHP module to be On.

To solve this issue you need to install this module on your server http://www.php.net/manual/en/mbstring.installation.php

If you are using cpanel please check this link http://forums.cpanel.net/f5/enable-install-mbstring-module-158165.html

Please also check http://tooltip.cminds.com/faqs/i-got-a-fatal-error-call-to-undefined-function-mb_strtolower/

https://ww.wp.xz.cn/plugins/enhanced-tooltipglossary/