7 Common Causes Of Runtime Error 91 In Vba And How To Fix Them

Runtime Error 91 in VBA (Visual Basic for Applications) is a common issue that developers encounter while coding in Excel, Word, Access, or other Microsoft Office applications. It usually indicates that you're trying to use an object that hasn’t been set or initialized properly. Understanding the common causes of this error and how to fix it can save you a lot of time and headaches. Let's dive in!

What is Runtime Error 91?

Runtime Error 91 occurs when you attempt to access an object variable that has not been instantiated. Simply put, your code is trying to reference an object that doesn’t exist yet. This can lead to the application crashing or producing undesirable results.

Now, let’s explore the 7 most common causes of Runtime Error 91 and how to fix them.

1. Not Setting an Object Variable

This is the most straightforward cause. If you declare an object variable but forget to assign an object to it, you'll get this error.

Solution: Always ensure that you initialize your object variable before use. For instance:

Dim ws As Worksheet
Set ws = ThisWorkbook.Worksheets("Sheet1")

2. Incorrectly Referencing Object Properties

If you reference an object property that doesn’t exist, you could run into Runtime Error 91. This often happens when the object is not correctly identified or the property is misspelled.

Solution: Double-check the object and its properties. Make sure you use the correct spelling and check if the property is valid for that object type.

3. Object Not Found

If your code tries to reference an object that doesn’t exist (like a worksheet that has been deleted), you'll run into this error.

Solution: Always verify that the object exists before you reference it. You can use error handling to manage these scenarios gracefully.

On Error Resume Next
Dim ws As Worksheet
Set ws = ThisWorkbook.Worksheets("SheetThatDoesNotExist")
If ws Is Nothing Then
    MsgBox "Worksheet not found!"
End If
On Error GoTo 0

4. Using Objects After They’ve Been Set to Nothing

Attempting to use an object after it has been released (set to Nothing) will cause this error.

Solution: Once you finish using an object, you can set it to Nothing but ensure you aren’t trying to reference it afterward.

Set ws = Nothing
' ws.Cells(1, 1).Value = "Test" ' This will throw Runtime Error 91

5. Scope Issues

If you declare an object variable in a limited scope (like within a subroutine) and try to use it outside of that scope, you'll get an error.

Solution: Ensure your object variables are declared at the appropriate level based on their intended use.

Dim ws As Worksheet ' Declare at the module level
Sub Initialize()
    Set ws = ThisWorkbook.Worksheets("Sheet1")
End Sub

6. Invalid Array Indexing

If you're working with an array of objects and try to access an index that doesn’t exist, this can result in Runtime Error 91.

Solution: Always validate your index before accessing the array:

Dim arr(1 To 5) As Worksheet
' Ensure you're within bounds before accessing
If index >= LBound(arr) And index <= UBound(arr) Then
    Set ws = arr(index)
End If

7. OLE Object Issues

When working with OLE objects (like forms or ActiveX controls) that are not correctly instantiated, you may encounter this error.

Solution: Ensure that any OLE objects you are trying to access have been created and are accessible in your context.

Dim oleObject As OLEObject
Set oleObject = Me.OLEObjects("YourOLEObjectName")
If oleObject Is Nothing Then
    MsgBox "OLE Object not found!"
End If

Troubleshooting Tips

If you encounter Runtime Error 91, here are some troubleshooting tips to guide you in resolving the issue:

• Check your Object Instantiation: Always use the Set keyword when assigning objects.
• Use Error Handling: Implement error handling to catch problems before they halt your application.
• Debugging: Utilize the debugging tools in the VBA editor (like breakpoints and watches) to track down where the error occurs.
• Review Object References: Ensure that objects you're trying to reference are valid and accessible in your code.

<div class="faq-section"> <div class="faq-container"> <h2>Frequently Asked Questions</h2> <div class="faq-item"> <div class="faq-question"> <h3>What does Runtime Error 91 mean?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>It indicates that you are attempting to use an object variable that has not been set.</p> </div> </div> <div class="faq-item"> <div class="faq-question"> <h3>How can I prevent Runtime Error 91?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>Ensure that all object variables are properly instantiated before use.</p> </div> </div> <div class="faq-item"> <div class="faq-question"> <h3>What should I do if I get Runtime Error 91?</h3> <span class="faq-toggle">+</span> </div> <div class="faq-answer"> <p>Use the debugger to find where the error occurs and check object initializations and references.</p> </div> </div> </div> </div>

To wrap things up, Runtime Error 91 can be frustrating, especially when you're deep into coding. But by understanding its common causes and following the solutions provided, you can effectively troubleshoot and fix this error.

The key takeaways are to always ensure your object variables are properly initialized and to employ good error handling practices. I encourage you to keep practicing your VBA skills and explore more advanced tutorials available in this blog for greater proficiency in your coding journey.

<p class="pro-note">✨Pro Tip: Always comment your code to remind yourself of the purpose of object declarations!</p>