Problem:
The user was getting a fatal error from WooCommerce Blocks.
Solution:
This error Call to undefined function mb_strtolower() means that the Multibyte String PHP extension(mbstring) is missing in your server.
Check with your hosting provider and ask to enable the Multibyte String extension. It is a Toolset requirement https://toolset.com/toolset-requirements/
If you are using cPanel or a similar hosting interface, you can enable it on the PHP extensions page.
