If you are getting the following error in your site, that means mbstring module is missing or not available.
PHP Fatal error: Uncaught Error: Call to undefined function mb_strtoupper() in
So, how to fix the mb_strtoupper() error in php?
For fixing this error, you have to install mbstring in the php.
Step-01) install mbstring extension (Ubuntu 18.04).
for php 7.1
sudo apt install php7.1-mbstring
for php 7.3
sudo apt install php7.3-mbstring
for php 7.4
sudo apt install php7.4-mbstring
for php 8.0
sudo apt install php8.0-mbstring
for php 8.1
sudo apt install php8.1-mbstring
Step-02) Restart apache server
sudo /etc/init.d/apache2 restart
or
sudo service apache2 restart
Now refresh the site page, mbstring error has been fixed.
