Why is “catch (Exception ex)” a problem?

Let’s consider the code below. In the try block there is a bug (null reference exception). This is then caught in the catch block and logged.

    string name = null;       
    int length = name.Length; // bug
catch (Exception ex) // why is this bad?
    // logging...
    Console.WriteLine(ex.Message + ": " + ex.StackTrace);

Why is this catch (Exception ex) a problem?

There is a bug in the try block. If the bug is just logged you are unlikely to notice there is a bug. You probably do not read all the logs all the time.

To be able to fix the bug you need to actually notice there is a bug. One way to do this is to let the program crash in case of a bug. Do not hide the bug, expose it!

Do not catch all exceptions but only catch specific expected exceptions.
Of course do not catch the NullReferenceException as this would again hide the bug.

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