Centos

to Open a specific port in centos you need to use these commands 

 firewall-cmd --zone=public --add-port=10000/tcp --permanent

then reload the firewall

firewall-cmd --reload
 

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

The sudo command provides a mechanism for granting administrator privileges, ordinarily only available to the root user, to normal users. This guide will show you the easiest way to create a new user with sudo access on CentOS, without having to modify your server’s sudoers file. If you want to configure sudo for an existing user, simply skip to step 3.

# Get all yum commands previously run
yum history list all

# Get the details of the command
yum history info [entry number]

# Undo each command top-down
yum history undo [entry number]

You have to be careful not to undo the initial system install!

# Get all yum commands previously run

yum history list all

# Get the details of the command

yum history info [entry number]

# Undo each command top-down

yum history undo [entry number]

Install Apache:

•      First, clean-up yum:

sudo yum clean all

• As a matter of best practice we’ll update our packages:

sudo yum -y update

• Installing Apache is as simple as running just one command:

sudo yum -y install httpd

Allow Apache Through the Firewall