This mini how to may be helpful for someone. I came across another Arcserve Backup 11.5 server that for some reason lost its caroot password. I needed to reset it to something the backup server administrator could remember.
Here are the steps to reset the password for caroot.
From the folder where Arcserve is installed run from a command prompt the following:
authsetup /p “passwordhere”
This should talk about a minute and come back with a message that said successfull.
If the above didnt work the first time try the following: ( this will restart the CA services). You could also reboot the machine.
Then try the authsetup command again.
ItFixed it for me so I hope it helps someone else.