@Thanatermesis
Confirmed the upgrade of 3.0.6 (32Bit) to 64bit is a total disaster (not really data wise, I cloned the disk to a virtualbox)
Installer messes up due to LVM or LUKS using sda. But switching off and rebooting is to no avail.
Opting for "no" (twice) does the trick and the installer continues.
I haven't tried everything yet but the glaring things are when booting (the updater should've sent you the reports around 19.00 Amsterdam time using my protonmail addres):
- The upgraded system boots straight into e17 (which was the default in 3.0.6)
- On logging out to get into e16, does not offer my $USER but "Elive User" and an old /home entry.
Chosing "other ... ' and manually entering my old $USER and password works.
*Programin former system that required a "service" to be run (own builtin mysql) is not there as a service anymore.
In E16 menu: - Most graphics apps are gone, leaving only Gimp and Gtkam
- audio only cplay
- video only Devede
- no soffice
etc, etc.
To be fair,quite some progs like soffice, inscape ,rage,vlc, etc. are there and can be started from terminal....but definitely not all.
Previously self installed apps like guake, mc, are not there anymore. - previously installed Java is gone
I will not touch the install for now as I suspect there's stuff to be examined. 
My advice to others:
If you have valuable data or programs
Do not upgrade 3.0.6(x32) straigh to 3.7.x(x64) !
Will try to go the 32bit upgrade another day, after I put 3.0.6 back in it's original state. 
