Hello Philippe,
I am afraid version 1.2.4 is somewhat historical.
To make everything work, you will need to follow the complete upgrade path - unfortunatelly I am not sure anymore, if online upgrade was available back in 1.2.4. I think not.
It might be okay just to backup your URLs, update the backup file using the URL update tool, install one of the first 2.x versions and then upgrade using online upgrade funciton. This COULD work... I do not say it WILL. We have never done upgrade from as old version.
But for sure, backup everything before you start!