Ok, the problem is caused by the change in minimum protocol version. In xenial, smb 1.0 is the default, but in bionic it's 3.0.
In the working xenial case, when I force protocol version 3.0 via "vers=3.0" in the pam_mount config, I get the same error as in bionic. The troubleshooting continues! -- You received this bug notification because you are a member of Ubuntu Server, which is subscribed to libpam-mount in Ubuntu. https://bugs.launchpad.net/bugs/1764778 Title: Problems with SSSD + pam mount To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/libpam-mount/+bug/1764778/+subscriptions -- Ubuntu-server-bugs mailing list Ubuntu-server-bugs@lists.ubuntu.com Modify settings or unsubscribe at: https://lists.ubuntu.com/mailman/listinfo/ubuntu-server-bugs