From your comment,
In a application with say ~10k source files, finding this place is the problem
In an application of this size, there should be some logging / tracing options built into the application. This is almost a requirement for applications of this size, including GUIs.
Among the logging / tracing options, one of the option should be to print out the location, class name, or the function name of the code being executed, even if the code being executed thinks that everything is going normally (without an exception). Depending on how logging is actually used throughout the application, this may require increasing the logging level to DEBUG or VERBOSE.
The code not detecting an abnormal condition when one has actually happened is in itself a software defect. Additionally, sometimes the current software behavior is exactly as the programmer has intended - except that it doesn't agree with the user's requirements or specification. In both cases, you will want to see the execution trace, not just the exception report.
Enable it, and see where execution hits while you perform the bug reproduction steps. Use the logs as the starting point for further investigation.
If the application does not implement adequate logging / tracing to allow you to investigate the bug, bring this issue to the project lead. If the application does not have any logging / tracing at all, I guess the problem is bigger than the code base itself, and it will require more people to solve.