Authentication Error when Changing User Passwords in Linux

Authentication Token Manipulation Error when Changing User Passwords in Linux :-
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Error on the screen  :-
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You may get an error, such as Authentication Token Manipulation Error, while trying to change passwords for a user.

For example :-

#passwd user

#Authentication Token Manipulation Error


*Note:- 


1)
      This error is being produced because you are using shadowed password files & the shadow does not have entry for this user. i.e, /etc/passwd has an entry for this user, but /etc/shadow does not.

2)
       In order to resolve this, you can either add the entry manually or recreate the shadow file. You can use pwconv to recreate the shadow file, See the manpage for more details on this.

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