Windows login doesn't allow, if username more than 20+ character


I have the Samba PDC setup in Ubuntu 16.04 & joined the windows clients fine. But the windows 7 doesn't allow the users, if their login characters are more than 20+. I tried UPN format also ( ), it didn't work! Can someone please help me!

Sivachidambaram GanesamoorthySr System EngineerAsked:
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Ajit SinghCommented:
The SAMaccount is limited to 20 characters for earlier clients:

However, In order to log in with more than 20 character account name, you must use a UPN logon.

The UPN is comprised of a logon name and the UPN suffix that must be appended to the name (the text following the @ symbol). The UPN must be unique within the forest.

By default, the user has a UPN suffix of "@domain_name". If multiple UPN suffixes are available, you can choose the desired UPN suffix from the list of UPN suffixes.

You may refer to the following link:

Users Can Log On Using User Name or User Principal Name

Hope this helps!
Do you have users with sAMAccountNames longer than 20 characters? If you do, you cannot log on. I don't think it will matter if you try logging on with UPN either. sAMAccountName cannot be longer than 20 characters. This is for backward compatibility with older Windows versions.
Shaun VermaakTechnical Specialist/DeveloperCommented:
I run into these limitations regularly. This one of the reasons I always use/recommend employee numbers as usernames.
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RaminTechnical AdvisorCommented:
To workaround this issue just type the first 20 characters of the password.
David Johnson, CD, MVPOwnerCommented:
@ramin it has nothing to do with the password BUT the samaccountname limitation of 20 characters
Shaun VermaakTechnical Specialist/DeveloperCommented:
I tried UPN format also ( ), it didn't work! Can someone please help me!
Please check under the account tab of the user properties if the UPN is actually configured
Sivachidambaram GanesamoorthySr System EngineerAuthor Commented:
Thank you so much for everyone for clarifying my doubts!
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