bug

Error : Notice: Undefined offset: 2 in vendor\magento\framework \Encryption\Encryptor.php

Some time you will have the below error after you move Magento2 from server to another server with different PHP version or even with the same PHP version , now what is the first solution we can do 

mostly this library will be missed 

php-sodium

So we need to install it , below is some command we can do to install it on Centos