[KevinH]

By any chance is Qt or Sigil compiled on Windows using the compiler equivalent to:

-fno-exceptions

If not, that really only leaves the possibility of a crash happening when the Error Dialog is waiting for the OK button to be pushed.

As BeckyEbook's debug output shows, the missing NCX runtime error is caught in the LoadFile routine in the right place but somehow it crashes after it shows the Error Dialog, ok button.

That is when Qt allows other QEvents to be processed which can be seen in the debug ouput as the MainWindow activation happening but in the first startup case of Sigil, it needs the m_Book properly set before it opens the MainWindow.

Perhaps we catch the runtime error, and immediately use CreateNewBook() *before* we display the Warning message as that might prevent the crash on initial startup It is worth a shot.