I upgraded VFP8 to VFP9, using the installation CD.
VFP9 seems to work well.
Attempts to install SP1 fail with this message:

“The upgrade patch cannot be installed by the Windows Installer service because the program to be upgraded may be missing, or the upgrade patch may update a different version of the program. Verify that the program to be upgraded exists on your computer and that you have the correct upgrade patch.”

Yet, VFP9 is installed in the default directory.
I also attempted SP1 installation with anti-virus software disabled.
I have administration rights.

Help please.