VBScript – Troubleshooting

Introduction to VBScript Troubleshooting

Practical Advice

• Your first thought should be:  ‘Is this VBScript error a syntax problem or there a fault with the logic?’
• Make sure that the file extension is .vbs and not .txt.
• Print out the VBScript and go through it line by line.
• Check your ‘ Rem lines
• Compare with a similar script that does work.
• Try running the VBScript on the server rather than a workstation.
• Try ‘Option Explicit‘ and make sure you have declared your variables.
• Experiment with adding Error Handling code.
• Beware running a script which creates ‘Objects’ for a second time.  It that’s your problem you are likely to get a WSH message:  Code 80071329  – Object Already Exists
• If you get a different 800xxxxx then check here

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Positive Thinking – Get into ‘State’

1) Believe in yourself

Firstly, and most importantly, believe that you can solve thisproblem!  Guy says, ‘You will beat this VBScript problem’.  So take 5seconds to get into ‘state’.  Visualise another script problem you solved,remember the elation you felt when beat it.

2 Collect information

A well defined problem really is half the solution.  Something magicalhappens when you write down precisely what is wrong.  Just collecting thesymptoms triggers your brain to start searching for causes.  As a bonus, ifyou write down the problem it will prepare you for other strategies.

3) Ask: ‘what has changed recently?’

What have you just added?  Which line did you copy and paste?  If soreverse engines, revert to how it was and see if that cures the problem. 

Pattern recognition is a vital troubleshooting skill.  Look for patterns,spot what is out of the ordinary, such as file name that is different, or aspelling misNake in a variable.

Basic Principles of Troubleshooting VBScripts

What I like to do when troubleshooting is keep halving the search area until the problem emerges.  The way that I narrow the search area is to ask a series of questions, for example, is the error down to syntax or logic.  A logical error would be trying to connect to a server or share that does not exist, whereas a syntax error would be a missing bracket or ampersand.

Here are pairs of questions each of which narrow the search area.  The problem is ‘Why doesn’t my VBScript work?’

• Is the problem Logical or Syntax
• Should we look at the VBscript or to Active Directory
• Server or Client (especially Win 9x)
• Is the error consistent or intermittent

Always remember that scripts mimic real life.  Therefore, walk through the actions manually and record all the steps.  For example, open Active Directory Users and Computer and manually create the user or amend the property sheet.  Now go back to the script and see if you can find the missing item.

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I like thePermissions Monitor because it enables me to see quickly WHO has permissions to do WHAT.  When you launch this tool it analyzes a users effective NTFS permissions for a specific file or folder, takes into account network share access, then displays the results in a nifty desktop dashboard!

Think of all the frustration that this free utility saves when you are troubleshooting authorization problems for users access to a resource.  Give this permissions monitor a try – it’s free!

Download Permissions Analyser – Free Active Directory Tool

Simple Tests for VBScripts

Can you run the script successfully on the very Windows 2003 server?
Simply double click the VBScript in isolation, away from a Group Policy.  This test will determine if you’re facing a pure VBScript problem, or if the error is assigning the script via Active Directory Users and Computers.

If absolutely nothing happens, check the file extension.  You need to save as with a .VBS extension.   Is security so tight that VBScript files are forbidden from executing?

In terms of strategy, break the script down into sections.  Get each section working in isolation, then paste all the sections together and so build the final script.

After you get the script working on the server, the next step it to run the script on the client.  Does it work on an XP Client?  Is the fault only with Windows 9x machines?

Do you get an error message in a Windows Script Host box?
When the VBScript fails, research each of the clues supplied in the message box.  Read the Error: Xyz message. 
Check the Line number in the message against the line number in your script.  Count all blank lines and comments. 

To determine the underlying cause the Code Number is the key, for example, Code 800A01B6 in the screen shot.  Lookup YOUR error Code: 800 number here

Three VBScript Troubleshooting Commands

On Error Resume Next

For a quick fix, try adding the command ‘On Error Resume Next’.  This tells the script to ignore the error and continue.  In my opinion this is seldom a permanent solution, however it will allow the script to get past the fault and possibly execute useful commands.  One possible use of this strategy is when you are mapping multiple network drives.  On Error Resume Next would skip the fault and at least VBScript will map the other drives.

Option Explicit

This command forces you declare all variables.  Where Option Explicit helps your troubleshooting is where you misspell a variable later in the script.  For example, you start off calling it strUser but then call it strUserS. 

Err.Number

Err.number is the first stage in introducing proper error-correcting code.  Combined with If ..then… End If, Err.number offers professional solutions to your problem.  The only trouble is that you need experience of both the If ..then structures and the possible logical outcomes.  Perhaps my ideas for err.number are best explained by an example:

See Also

• Getting Started
• Error Handling
• Option Explicit
• WSCript.Echo
• VBScript Home