I just installed Ubuntuy 18.10 on one of my computers, and am trying to understand why a series of passwords are not working, even though they are completely random character strings.

I started by trying to change the initial password to the following character string: XB76cD_*P789_;Eqy10

I receive the following error and was prevented from using the password:

Try to avoid common words.

As far as I know, this string is not a common word in any language so I started to dig into it deeper to see why this password was not allowed.

The fresh installation is still using the default pam_unix module to validate changed passwords, so I looked in: /etc/pam.d/common-password , and did not see any rules that would make this password invalid.

I then started trying slight variations of the same password to dig a little deeper into why the random password was not allowed. I started to find slightly different variations of the password that were also not valid:



[.] B76cD_*P789_;Eqy10

It seems as though there is a regular expression set somewhere that is preventing me from using a lot of passwords which should be valid.

This only occurs when attempting to set the password from the change password option in the top right drop down.

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Changing the password via the terminal using passwd still allows the password change.

Does anyone have any idea as to what I should check next to be able to determine why these passwords are not valid?

  • 2
    Just for completeness' sake: by which means are you trying to change the password? – tink Jan 3 '19 at 8:00
  • Whatever "the top right drop down" is, is the thing that's at fault. You've demonstrated that because passwd works as expected. – roaima Jan 4 '19 at 17:09

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