roperties:server_props&" target="_blank" rel="nofollow">http://valentina-db.com/docs/dokuwiki/v9/doku.php?id=valentina:vcomponents:vsql:referenceroperties:server_props&;s[]=maxtransfertimeout#maxtransfertimeout

It's the time limit for sending/receiving any single command or result to/from the server.
So it would be depend on both - network speed and data size.

Ok. What's happening if the vServer engine is reaching this limit ? Is there a Exception raised, a vDatabase.errorNumber set or only part of cursor sent (silently failing) ?

It would be connection termination, and yes, it seems it would be "just disconnected" for vClient. But this param is used mostly for testing - not in real life. Could you describe why do you need it more detailed?

I try to find an error (or a cause) in my client/server app that seems sometimes to crash the vServer (on a new MacMini, MacOS 10.4.6) or sometimes drop the connection. And most of the time, unfortunately (!), the same manipulation work as expected.

sometimes to crash the vServer (on a new MacMini, MacOS 10.4.6)

Please, send me crash logs.

The server don't give me crash log and my application catch the vException given by the connection drop. Currently I have just the Realbasic/Xojo exception stack. The vServer stop and restart automatically. Must I set some parameter in order to see crash log ?

You may run vServer manually.

Find /Library/LaunchDaemons/com.paradigmasoft.vserver_x64.plist
Set
KeepAlive = false;
RunAtLoad = false;

And run /Library/VServer_x64/vserver_x64.app/Contents/MacOS/vserver_x64 in the terminal.

Also, you may try to find crash logs in ~/Library/Logs/DiagnosticReports or /Library/Logs/DiagnosticReports

https://apple.stackexchange.com/questions/26480/where-can-i-find-my-crash-logs

Ok. Found one in /Library/Logs/DiagnosticReports. Here it's attached.
I thank you to take a look and try to help me. But don't take too much time on it thought because I'm on an old release with this application (V4RB 5.8.8 and VSRV 5.8.5, with RealBasic 2011r4.3) and I don't want you loose your time.

Reading this crashlog, I see the crash is on a vCursor.DeleteAll command. Why is it crashing sometimes and not always is a mystery for me at this moment.
In the calling procedure,
1) I create the vCursor (it's a subClass of vCursor) : myCursor = new myCustomCursorClass(someParameter)
2) I test vCursor <> nil AND vCursor.RecordCount > 0
3) I iterate the vCursor (vCursor.NextRecord), doing some update on other records (other table) upon the value of each vCursor record
4) After this, if all updates were ok, I send the vCursor.DeleteAll command
Mmmh, I think about one thing : perhaps is it safier to select the first record (vCursor.FirstRecord) before send the DeleteAll command ? To test.
Other tough : Perhaps I must test the connection before 4) because the connection could have dropped in 3) And thus the problem appear previously. But not so funny if I must test the connection before each command...