You are a genius!!! Thank you very much! I'm staying with Firefox 52 ESR because my Scrapbook didn't work with Quantum.
I installed ScrapBee on Windows7. I had Scrapbook Plus.

Some things to fix:
1) I had a little problem with the installation:
First, you have to launch the install.bat in a prompt administrator, otherwise you got "Access denied" error when it tries to wirte in the registry;

2) Then, in the batch file I changed the two lines as:
reg add "HKEY_CURRENT_USER\Software\Mozilla\NativeMessagingHosts\scrapbee_backend" /d %USERPROFILE%\Downloads\scrapbee\scrapbee_backend.json /f
reg add "HKEY_LOCAL_MACHINE\SOFTWARE\Mozilla\NativeMessagingHosts\scrapbee_backend" /d %USERPROFILE%\Downloads\scrapbee\scrapbee_backend.json /f

I changed the command %cd%\
with
%USERPROFILE%\Downloads
because %cd% pointed to my System32 folder, instead of Downloads folder (because I run the batch file with System32's cmd.exe).

3) All my old elements in the original rdf file with a type as "NS18:type="combine" (more pages in one), or
"NS18:type="site"
don't work, but if I empty the tag with a empty string
for ex.: "combine" --> "" in the scrapbook.rdf file, I can load the pages.

That's all for the moment. If I'll find others glitches, I write them to you.
Thanks again. I can install the new Firefox version, now! :-)