Juniper error missing mandatory statement 'root-authentication' | requie change of case, digit or punctuation

error: comit failed: (missing statements) Commit command is not working | how to save running configuration on juniper in gns3:

Error Message detail:
Junos version= JunOS Olive 12.1R1.9
error messge= missing mandatory statement 'root-authentication'
error image=

The reason or causes of this error:
  juniper router running JunOs have the default user name "root" with not password. Whenever you want to commit or save some changes/configuration using commit command & no password is set for root user then it will show you the above error that is "missing mandatory statement 'root-authentication' "

How to save current configuration on Juniper:

In order to commit change or for saving current configuration on juniper router you have to set the root password. You can set the root password on juniper router with following commands:

cli
configure
set system root-authentication plain-text-password (press enter)
now type the root password and press enter. Remember you are required to set a strong password with alpha numeric characters otherwise it will show you error messages
error: minimum password length is 6
error: requie change of case, digit or punctuation 
 and you will need another try with a password having letters and numbers..

once you have  successfully set root password, now you will able to save the current configurations & your commit command will also works fine. If you want explore Juniper commands and want to learn more about configuration of juniper on gns3