Catching base Exception class in .NET

Question

I keep hearing that

catch (Exception ex)

Is bad practise, however, I often use it in event handlers where an operation may for example go

Answer 1

This is all good of catching exceptions that you can handled. But sometimes it also happens that due to unstable environment or users just do the process correctly, the application runs into unexpected exception. Which you haven't been listed or handled in code. Is there a way that the unhandled exception is captured from app.config file and displays a common error?

Also puts that details exception message in a log file.