I reedited my sources list and this time i used the other apt line, i.e. deb http://www.remastersys.klikit-linux.com/repository/
remastersys/...and it worked! Now i would like to make a complete backup and include selected user data because as it is the file ends up being larger than 4 GB. How do i exclude data, there is an option called Modify but clicking on 'files to exclude = ' doesn't give me the file browser or anything like that, from which i could select files to exclude, nor can i type anything there; it just takes me back to the original menu. Is moving extra stuff elsewhere the only option? I remember we did use to have a 'files to exclude' option that worked before (about 5 - 6 months ago).
Edit: After a first use, even this Remastersys doesn't open from the Menu, same error message. I got around it with this command: sudo remastersys-gui.
Would appreciate it though, if i could know why Remastersys gives that error message and won't open from the Menu, might learn something from it.