Cannot switch user from autologged account to another account

My computer is running Ubuntu 17.04 and has my wife autologged in. When I want to switch to my account, by clicking to switch at top-right desktop:

This works most of the times, but sometimes I just get a black screen.

I extracted a piece from /var/log/auth.log when it occurs:

Aug 31 21:43:09 olimpio lightdm: PAM unable to dlopen(pam_kwallet.so): /lib/security/pam_kwallet.so: cannot open shared object file: No such file or directory 
Aug 31 21:43:09 olimpio lightdm: PAM adding faulty module: pam_kwallet.so
Aug 31 21:43:09 olimpio lightdm: PAM unable to dlopen(pam_kwallet5.so): /lib/security/pam_kwallet5.so: cannot open shared object file: No such file or directory
Aug 31 21:43:09 olimpio lightdm: PAM adding faulty module: pam_kwallet5.so
Aug 31 21:43:09 olimpio lightdm: pam_succeed_if(lightdm:auth): requirement "user ingroup nopasswdlogin" not met by user "robson"
Aug 31 21:43:09 olimpio lightdm: pam_unix(lightdm:auth): conversation failed
Aug 31 21:43:09 olimpio lightdm: pam_unix(lightdm:auth): auth could not identify password for [robson]

At this very time, I see this in /var/log/syslog:

Aug 31 21:43:09 olimpio lightdm[1618]: Stopping PAM conversation, interaction requested but not supported

I have to reboot my computer at this point, because my session is planned to execute scripts at DISPLAY :1, if I log at DISPLAY :0, my scripts will cause a problem.

Can anyone help me? I found that there are two similar issues (127147 and 635978), but those didn't solve my problem.