I turned on logging a few WinSCP sessions ago, and all was fine. Then this morning during file transfer from remote linux server, "Error occurred during logging. It's been turned off.", "System Error. Code: 32. The process cannot access the file because it is being used by another process." I did not have the log file open, nor had I recently.
This dialog could be dismissed but it would pop up again immediately. I tried dismissing it several times, including holding down the ENTER key for a bit to dismiss it probably neart to a hundred times, and gave up. Eventually killed WinSCP with Process Explorer.