session_start(): Failed to read session data joomla

In this post we will resolve problem that occures ofently:
This problem is due essentially to MySQL connection
1- Verify your SQL connection (Servie is up)
2- Connect with your joomla user to database
   mysql -u your_user -p 
   Enter your password
3- You may have this errror
    ERROR 1524 (HY000): Plugin '*F70658E9BDD2910AC33ACDA164605DFC1DA70A68' is not loaded

4- All right: this proble occures when MySQL password encryption is not supported.
    4.1- Login with root
           

 mysql -u root -p Enter your password;
use mysql;
update user set authentication_string=PASSWORD("your_password") where User='joomla_user';
update user set plugin="mysql_native_password" where User='joomla_user';
flush privileges;
quit;

--> Now refresh your website page and it works

Sometimes we need to restart MySQL for unknown bug, then u can run:
1- mysqladmin.exe -u root -p shutdown
   <Enter your root password>
2-  mysqladmin.exe -u root -p start
   <Enter password>
End go to 4th statement above.

Tested on MySQL 5.7.17 Community Server
             Windows 10 [version 10.0.18362.720]
             Php 7.1.3
             Joomla 3.9.16