In order for your older Backup file indexes and media database to be compatible with the new indexes created with newer releases of Backup, they must first be converted.
The indexes are automatically converted the first time you start the Backup daemons. Before you install the Backup software:
Make sure that you have a recent, full backup of the file indexes (/nsr/index), server resource files (/nsr/res), and media database (/nsr/mm).
For automatic index conversion, make sure the amount of free disk space is double the size of your largest index. If you do not have enough free disk space, remove the indexes when you remove Backup, and recover and convert them according to the instructions in "How to Recover the Server Index and Media Database".
Remove the earlier version of Backup (but not the indexes) using the instructions in "How to Remove the Backup Software".
Install the Backup software.
You do not need an update enabler code to update from version 5.0.1 to 5.1.