ubuntu使用sudo passwd username修改密码后，打开应用程序，弹出如下错误信息对话框：
Unlock Login Keyring
Enter password to unlock your login keyring
The password you use to login to your computer no longer matches that of your login keyring.
…
解决方法如下：
点击左侧Launcher栏ubuntu按钮，在Search your computer搜索框输入pass或者key，打开Passwords and Keys，右键点击Login，选择Change password菜单，输入原来的密码（sudo passwd修改前的密码），再输入新密码（sudo passwd修改后的密码）即可。
参考文档：
How to get rid of “Enter password to unlock your login keyring” prompt in Ubuntu – Black God
Ubuntu uses Centralized password management tool called Seahorse. This tool is a front end GUI to GNOME’s keyring management system. In simple this tool stores all passwords with a master password which is normally same as login password. This tool can manage your PGP keys, SSH Keys and pass phrases we use in different applications in Ubuntu.
You can find the Seahorse tool in Ubuntu main menu -> Applications -> Accessories -> Passwords and Encryption Keys.
In practical I face a problem once I change my login password. You can change password either through System -> Preference -> About me -> Change Password… or you can use shell command passwd. I use to change my password in either of these ways. In both the cases, I encounter Enter password to unlock your login keyring prompt dialog box during my first login after changing password.
SeaHorse uses your login password as master password to unlock its pass phrase storage box. When you change the password, it is NOT updated to SeaHorse (at least, this is what I believe). So the new login password fails to unlock Seahorse storage box.
The simple command line way to do it is to remove the ~/.gnome2/keyrings/login.keyring.
In GUI way:
Step-1: Ubuntu main menu -> Applications -> Accessories -> Passwords and Encryption Keys
Step-2: In Passwords tab, right click Passwords: login. In the menu select Change Password… option.
Step-3: Enter your old login password and new login passwords.
You are done. Next time, it won’t ask for any login password for GNOME keyring. If Ubuntu integrate this change while changing the user password, it would be better user experience.