ORA-16024: parameter LOG_ARCHIVE_DEST_1 cannot be parsed
I had chosen to disable archiving as one of the options for DBUA, but was really surprised to see this error. After a little bit of research I found Metalink Doc 96278.1.
Turns out this error was happening because we had log_archive_dest along with log_archive_dest_1 set -- the kicker was it was set to be blank. Here's the relevant info from the pfile:
So the trick was to completely remove the entire *.log_archive_dest='' line from the pfile and DBUA was able to proceed with the upgrade without the ORA-16024 error.