VBA and VB6 Debugging Options

In this blog post I will explore the VBA Debugging options.
If you go to
Tools - Options - General

You will see the Error Trapping Options

1) Break on All Errors
2) Break in Class Modlue
3) Bread on Unhandled Errors


Depeding on whether you have an error hanler active or not, or if you call the a class of modue function you will get different behavious. Let's test them out.

1) Break on all errors. 

      Caller is a Sub of Function
          It stops at all errors as soon as they occur: ex division by zero or Err.Raise

      Caller is an Excel UDF.
         The code will NOT STOP. It will just end execution at the point where the error is caused
         Excel will Return #VALUE!


2) Break in Class Module

     Caller is a Sub or Function
          It stops only on Unhandled errors. If it meets an Err.Raise in a Class module it will stop
          in any case.

    Caller is an Excel UDF
          It terminate only on Unhandled errors. If it meets an Err.Raise in a Class modue it will raise
          Err.num 440, irrespective or the error number raised. VERY STRANGE
 
3) Break on Unhandled Errors
      Caller is a Sub or Functin or UDF.
      It stops only on Unhandler errors.


As you can see Opton number 3 is the one that gives the most consistency, followed by option number 1 and
finally option number 2.
I would recommend to use always "Break on Unhandled Errors" and switch to any of the other two options only if you are debugging difficult code.
Option 2 is interesting especially when you are developing an ActiveX component and you want to stop the debugger in the class.

Again, use "Break on Unhandled Errors" and you will save a lot of time trying to put up with the inconsistency between on how the debbuger behaves in case you are using an Excel UDF or just simply a sub or function.