Making Your Script Unstoppable – Advanced Error Handling

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In the SCM Automation Lab, we don’t just write code that “works.” We write code that lasts.

If you click your automation button while SAP is already logged in, or if you have a typo in your server name, a basic script will simply “crash.” Today, we will learn how to make your VBA script smart enough to handle these unexpected situations.

Step 1: Handling “Already Logged In” Sessions

The most common issue is trying to log in when you are already in the middle of your work. We need to check if a session exists before opening a new one.

The “Smart” Connection Logic

VBA

' --- SCM Automation Lab: Error Handling Edition ---
Sub Smart_SAP_Logon()
    Dim SapGuiAuto As Object, SAPApp As Object, SAPCon As Object, session As Object
    
    On Error Resume Next ' If an error occurs, move to the next line
    
    ' Check if SAP is already running
    Set SapGuiAuto = GetObject("SAPGUI")
    If Err.Number <> 0 Then
        MsgBox "Error: SAP Logon Pad is not open!", vbCritical
        Exit Sub
    End If
    
    Set SAPApp = SapGuiAuto.GetScriptingEngine
    
    ' Check if a connection is already active
    Set SAPCon = SAPApp.Children(0)
    If SAPCon Is Nothing Then
        ' No active connection? Then open a new one (Login logic goes here)
        ' [Insert your Login code from Post 2 here]
    Else
        ' Connection exists? Just grab the active session
        Set session = SAPCon.Children(0)
    End If
    
    On Error GoTo 0 ' Reset error handling back to normal
End Sub

Step 2: The “Object Not Found” Protection

Sometimes SAP takes a few extra seconds to load a screen due to network lag. If VBA tries to type into a field that isn’t visible yet, it will fail.

The Solution: Simple Validation Instead of just waiting blindly, we can check if the SAP window is actually ready.

VBA

' Example: Checking if the MB52 screen is ready
If session.ActiveWindow.Text <> "Warehouse Stock" Then
    Application.Wait (Now + TimeValue("0:00:01")) ' Wait one more second
End If

Step 3: Friendly Alerts for Users

Instead of a scary “Runtime Error 1004” message, we should provide clear instructions.

  1. Wrong Server Name: “Please check the Connection Name in Cell A1.”
  2. Invalid Password: “Logon failed. Please verify your SAP Password in Cell A3.”

Lab Lead’s Pro-Tip: The Exit Sub Command

“Know when to quit.” Using the Exit Sub command inside an error check is vital. It stops the script immediately so it doesn’t try to run subsequent steps on a non-existent SAP window, which would cause even more errors.

Wrapping Up

You have now mastered the art of Bulletproofing. Your SCM tool is no longer just a macro; it’s a robust piece of software that can handle the chaos of a busy office environment.

What’s next? Now that our data extraction is stable and error-free, it’s finally time for the Grand Finale: Power Query. In the next post, we will transform our messy SAP raw data into a beautiful, automated SCM dashboard.

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