>>>Hello. I have some clients using VFP 6 apps that I wrote years ago. What is the highest version of VFP that I can recompile these apps in?
>>>
>>>I tried VFP 9, but that did not work. Need too many mods to get then working.
>>>
>>>(I originally built these on the frameworks of VFX and SDT)
>>>
>>
>>What is the point in upgrading to any other version than VFP9?
>
>I can't go to 9 because it would be too much work. But I would like to get more stability and take advantage of some additional features that may be in a new OS.
>
>(The number of support calls I get have gone up as clients upgrade their OS and infrastructure.)

I doubt you would have less problems upgrading to any other VFP versions. You should either upgrade to VFP9 or forget about VFP at all and move to some other language.