>>>If you can use a debugger, set a watch expression on SELECT("Main_Cursor") and put a Set Step On in form's .load(), then it should stop twice: once the cursor is created (it would show a non-zero value) and next when it's closed (becomes zero).
>>
>>Unfortunately, I tried this approach. And I never get the cursor closed on my system, during testing.
>>This happens to some customers. And mostly in a couple of methods where the code "determines" that the cursor is closed. So the cursor gets closed in a method before the one where the error occurs.
>>I will have to place many test codes - checking if the cursor is closed - at design time. And maybe this will catch the problem. I suspect, but I can't prove, that the cursor is closed because something happens to the desktop.
>>Although I don't know for sure.
>
>A few general things to consider:
>
>- If you're using multiple datasessions, are you unexpectedly switching between them?
>- Are you implicitly closing your table by opening another one in its work area - maybe you're forgetting an "... IN 0" clause in a USE command or something similar?
>- Are users selecting an unexpected work area by clicking on a grid or some other control?
>
>I use defensive coding like this when opening tables, running SELECTs or doing other data munging:
>

>FUNCTION MyFunc
>LPARAMETERS ...
>
>LOCAL lnSelect
>lnSelect = SELECT( 0 )
>
>* Data munging goes here...
>
>SELECT ( lnSelect )
>
>RETURN
>

>Another defensive technique is to ensure a table is open before doing anything which requires it - if not, open it. This doesn't pinpoint why a table is being closed unexpectedly but minimizes the impact of that happening.

I do not use datasessions. I do not open tables. Everything I do is based on the Cursor Adapter (CA). I have my own biz object, for each table in the application. So, on any particular form, at design time, I drop the biz objects of each table.
And the CA automatically opens the CA view/cursor for each table. These views are open for the life of the form.
And I do have a "defensive" code now that checks if the main CA view is open; in certain places. And if it is not open, the code write the error in a hidden LOG. Then periodically I check this log. For most customers I never see anything in this LOG. But a few, on occasion, have entries in this LOG. Sometimes, once a month, or once in a 6 months. No reasonable explanation.
And I keep adding these "defensive" checks if the CA view is open. But when I checked the log of a few customers (just today), they show that the CA view/cursor was not open in certain places. But I don't see how the view was closed. This is what I am trying to determine.