>In Windows 10 (64bit) I cannot update Thor tools.
>The line
>"llReturn = Execscript (_Screen.cThorDispatcher, 'Thor_Proc_SetLibrary', 'VFPCompression.fll')"
>is answered with the error message "library file VFPCompression.fll is invalid"

If you installed Thor in any place below a system folder, i.e. any place specially controlled by Windowses (like %appdata% etc) then this kind of thing can happen, it will make things faster for you in ways you won't like.

My solution, while I still had Windowses, was to never use C: drive for my stuff. Initially it was because there was never enough space on it, it got wiped on reinstall, it got wiped on crash... but later specially for these kind of things too. Even the apps I installed didn't go to program files, they went to some place like q:\apps\thisapp.

So... reinstall somewhere else?