>Hi Alex,
>
>VFP 8 and 9 both predate mysterious intermittent access/concurrency issues associated with Windows 10 and later.
>
>I know it's a VFP8 app, but it might be worth experimenting with VFPA that automatically retries various disk interaction commands (copy etc) in case there's one of those brief OS issues. It usually defaults to 3 retries behind the scenes which appears to be enough.
>
>The other one to consider is virus scanning: if a scanner seizes something that VFP thinks is exclusively open, you can see index or other unexpected errors that disappear after a debug pause or reindex.

Hello John, and thanks for the info.

Indeed, those "ghosting" events across MSFT networks / Windows 10 OSs. This site has been struggling with for ages with "Error Reading File" errors that are absolutely random in terms of when they occur, as well as what type of file they target (DBFs, CDXs, FXPs, FRTs, etc.). A real pain, for sure!

Good thought, but I think it's safe to rule out access latency caused by AV software. Reason I say that is I can get to just before the COPY TO is issues and wait for as long as I want (i.e., let AV do its thing), then let the COPY TO run and I will get Error 20 the first time.

Thanks.