After upgrading our SRX300 from 15.1X49-D100 to 17.3R1 yesterday everything continued to work just fine, except that we now get an "access denied" error when trying to login via ssh.
The OS upgrade was done via SSH from the uploaded local OS image file. Config validation was successful, no errors whatsoever. After rebooting the box came up fine with the new OS version. We were able to use the previous root password to login to Jweb.
During troubleshooting we generated another user with super-user privileges, and this user can login via ssh an jweb. Changing the root password was possible, but even with the new root password only jweb login is possible. system.log error is: '<fw-name> sshd 14613 - - error: PAM: authentication error for root from >ip>'
The 17.3R1 Readme does not mention any changed behaviour for ssh root access. Is this a bug?