in LMS 3.x it was possible to start the installation with the "nobackup" option like:
I do not know if this option still exists with the LMS 4.x train but you could give it a try
Assuming you're upgrading on the same host or appliance, you can do a direct upgrade to LMS 4.2 from version 4.1 (or 4.0.1). No backup is necessary - your configuration and any data will migrate directly. (Reference)
Of course you can always do a fresh install and rebuild from scratch too.
Marvin, you are correct, a direct upgrade does not need a backup to get back all your data, but I think the installation process does a backup automatically - at least this was the case last week, when I performed an upgrade on a windows machine (from LMS 4.1 > LMS 4.2) and I assume that's what Elisabeth wants to avoid.
In any case, disable any anti-virus software during the upgrade procedure. This will speed up the installation and also prevents any failures caused by AV software.
The option -nobackup exists and works fine. Be carrefull to desactivate your AV software because the installation can stuck at "check lock files".
Without any backup?
Would it be better to remove the old LMS, clean up ( free tool available).
Then run the LMS4.2 from fresh.