The only real problem seems to be with COM servers. A minor issue is that OCX now requires a VCX, where as before a PRG declaration was all that would be needed.

There is also ERROR 78 related to SQRT and LOG functions. In interpretive mode or IDE EXE when decimal significance approaches about 30 digits an ERROR 78 is raised. However, an MSI install, with the VCRUNTIME DLL in program folder, works perfectly.Go figure.

With COM (VFP DLL) it's a bit trickier. You can see for yourself - download the ado query analyzer in the download section (it builds a DLL). Compile it in VFP 6 (i think it works under 8). Then compile it in VFP 9 (it breaks). I wrote Hsia about this issue - but no response. I did not learn about it until I tried to move a VFP IIS COM from 8 to 9. It seems that VFP 9 does not like COM's (DLLs) that issue a CREATEOBJECT .


>Hi
>
>I use with VFP8.
>
>It's native step to upgrade to VFP9, but I afraid obout errors (code,data, any other), especially something that invisiable problem that I can discover too late.
>
>I will appriciate information that will cover all potential risks and resolving/ignoring (as set enginbehivr) options.
>
>It is very critical step for me.
>I heard about 'No pain no gain' but I want to know the pain potential.
>
>
>Big thanks