Problem is, the app runs fine for several hours and then crashes for some reason I cannot understand because it does not open an Winbatch Error Dialog nor does it crash so that a windows fatal exception window would occur. It simply terminates quietly with exit code -1073741571. This I know because meanhile I wrote a wrapper program which starts the compiled Server App and logs the return code. Also the amount of hours it runs is not a constant value. For example the first time it ran over 9 hours and terminated, the second time it ran about 8 hours and then exited.

Does anyone have a solution to this problem or an explanation what this exit code means? I would be really grateful, cause this app should run permanently and not terminate itself after some hours.

retcode = qConnect(hdbc, Datasource, "", "")

Here's the complete subroutine which is called before every query. Of course there's also a disconnect subroutine, which I can post as well if you like:

DefineSubroutine ODBC_Connect(datasource)
DebugTrace(@on,gvRead("logfile"))
henv = qAllocEnv()

If henv == -1
retcode = qLastCode()
xMessageAndMail("Fehler %retcode%","could not allocate SQL Environment Variable", GetIcon("@mbstop"))
CleanUp()
Endif

hdbc = qAllocConnect(henv) 

If hdbc == -1
retcode = qLastCode()
xMessageAndMail("Fehler %retcode%","could not allocate SQL Connection Handle", GetIcon("@mbstop"))
CleanUp()
Endif

qSetConnOpt(hdbc, 103, 5, 0) ; SQL_LOGIN_TIMEOUT
qSetConnOpt(hdbc, 101, 1, 0) ; SQL_READ_ONLY

tries = 3
cnt = 0
while @True
retcode = qConnect(hdbc, Datasource, "", "")
If (cnt > tries) Then Break
If (retcode == @qSuccess) || (retcode == @qSuccessInfo) 
Break
EndIf
cnt=cnt+1
TimeDelay(1)
EndWhile

If (retcode != @qSuccess) && (retcode != @qSuccessInfo)
err=ODBC_Error_Ext(hdbc,1)
xMessageAndMail(StrCat("Fehler",err),"Could not connect to Datasource%@CRLF%Please check that a User DSN with Name '%datasource%' exists", GetIcon("@mbstop"))
CleanUp()
Endif

hstmt = qAllocStmt(hdbc)

If hstmt == -1
retcode = qLastCode()
xMessageAndMail("Fehler %retcode%","could not allocate SQL Statement Handle", GetIcon("@mbstop"))
CleanUp()
Endif

return hstmt ; Statement Handle
#EndSubroutine

I always keep my extenders up to date with vcheck.

The failing qConnect SQL return code is "[S1000 Simba Driver][Simba File System Base]", which is according to the creator nothing to worry about, you just have to reconnect. And It really happens very, very, rarely. Maybe 1 of 100 connects or so.

So I went looking for another driver using google for a newer/fixed driver and I found a newer release (from another vendor, not the one I got my driver). Now with this release I can do 356 connects and with this driver the app doesn't exit silently, it crashes winbatch.exe (or if compiled the compiled exe) and when you look at the details you see that the 4D Open odbc driver dll caused the crash.