On DB2 Windows (not sure about Linux/UNIX) I believe that the program is automatically run for you during fixpack install and instance update. You should not be running the program with the -a option, since that is forcing the changes to be made even if they were previously made for you (or if you previously ran the update program).

Here is the usage note:

"Thus, if the command [db2updv95] is issued more than once, no errors are reported and each of the system catalog updates is applied only once. However, if you wish to forcefully reapply all of the updates, you may do so by appending the -a parameter."

So maybe if you forcefully try to reapply the changes and the changes have already been made, then perhaps you get an error. Run it again without the -a option. Don't use the -h option either unless you only want to see the help info (and not run the program).