I have found that it is possible your ERS 5000 switches to lose the local password during the upgrade from earlier software versions to 6.3.x. If you use RADIUS authentication for CLI access, you may not realized that passwords have gone back to defaults.
Version 6.3 introduces Unified Authentication, where passwords are the same whether stacked or not. I had noticed this after remotely upgrading and finding no Telnet/Web password type assigned, which I set back to my default RADIUS selection. I only noticed when setting back to Local Password type when doing some configuration testing and couldn't log back in with my local RW password. Since I had the SSH code on the switch I found the default Secure code RW password - it didn't work either. Finally, tried the non-secure code default RW password, which allowed access to the switch.
So, make sure you go back and check your Local Password for RO and RW after upgrading to 6.3.x code.
