I have a customer that has been running our application since 1994!

It is an application that we have about 30 sites running and has started in DF2.3 and is currently in DF19.0

They are running on MSSQL using the DAW's CK

About 6 weeks ago, they upgraded their server from Windows 2008 to Windows Server 2019.

The application runs fine, but there is one really odd thing that I can't seem to nail down.

When the application needs to access a file that is on the network share, it fails if the application has been open for a length of time (say 30 minutes, maybe). They restart the app and it runs fine until it needs to again access a file on the share and it fails again until they exit out and restart.

It was happening at first when it wanted to open the only embedded file that we had (all others were MSSQL). They would restart and it would be fine. So I ported that last embedded file to SQL, then it failed whenever it needed to read report template files (List & Label) when they wanted to print a report. L&L invokes a DLL which then reads a template file on the same network share where the INT files are. If they exit the app and restart, then it will work for a period of time and then start failing again.

Here is what I did. I asked the client, when the failure happened, instead of exiting the app, open Windows explorer and browse to where the templates were on the share, then retry.
He reported back that he could browse to the files but the application still would not work until he exited out and restarted.

NEXT, I totally removed SMB1 from the workstation thinking that forcing it to only use SMB2 would provide a change in behavior, but it did not.

Has anybody got any ideas for this one?