Unable to change AppointmentItem.Start property


Senior Member
Outlook version
Outlook 2016 64 bit
Email Account
On some items of type AppointmentItem, I can set the Start property either as data type String or Date, other items of same type (I verified this by use TypeName (item)), I get either 'object does not support method' (if item declared as Object) or 'type mismatch (if item declared as AppointmentItem). The best clue I can think of is some appointments are created via VBA - those work properly to set Start property. Appointments created via Outlook UI get the error trying to set the Start property. Visually both appointments (created by VBA or via Outlook UI) look the same - baffled by the randomness of the error.

I tried the following without success:
1) Declared item as AppointmentItem - error changed from "object does not support..." to "type mismatch"
2) Declared and passed NewDate as String

Here's the code:

Sub ResetApptStartTime()
Dim CalFolder As Folder
Dim folders As folders
Dim FolderCount As Integer, ItemCount As Integer
Dim NewDate As Date

'Set CalFolder = Session.GetDefaultFolder(olFolderCalendar)
Set CalFolder = ActiveExplorer.CurrentFolder
NewDate = Format(Now, "mm/dd/yyyy")
If (WeekdayName(Weekday(NewDate)) = "Saturday") Then
NewDate = DateAdd("d", 2, NewDate)
If (WeekdayName(Weekday(NewDate)) = "Sunday") Then NewDate = DateAdd("d", 1, NewDate)
End If
NewDate = NewDate & " " & #11:59:00 PM#
ProcessCalFolders CalFolder, NewDate, FolderCount, ItemCount
Debug.Print "Folders processed: ", FolderCount, "Items processed: ", ItemCount

End Sub

Sub ProcessCalFolders(CalFolder As Folder, ByVal NewDate As Date, FolderCount As Integer, ItemCount As Integer)
Dim SubFolder As Folder
Dim PartialSubject As String
Dim PrevDate As Date
Dim item As Object

On Error GoTo ErrHandler
FolderCount = FolderCount + 1

For Each item In CalFolder.Items
If item.Class <> olAppointment Then MsgBox "The folder you selected contains non-appointment items, aborting": Exit Sub
PartialSubject = Left(item.Subject, 50)
PartialSubject = Replace(PartialSubject, vbCrLf, "")
PartialSubject = Replace(PartialSubject, vbLf, "")
Debug.Print PartialSubject
PrevDate = item.Start
If Now > PrevDate Then
item.Start = NewDate & " " & #6:00:00 AM# 'THIS LINE GENERATES THE ERROR
item.End = NewDate & " " & #6:00:00 AM#

' item.Save
Debug.Print "Subject: ", PartialSubject, "changed from ", PrevDate, " to ", item.Start
ItemCount = ItemCount + 1
End If
For Each SubFolder In CalFolder.folders
ProcessCalFolders SubFolder, NewDate, FolderCount, ItemCount
Exit Sub

Debug.Print Err.Number, Err.Description
Resume Next

End Sub
Last edited:
It turns out that nearly all of the manually created AppointmentItems are recurring and I guess there's no option in VBA to modify the start date/time of a recurring appointment (is there?). Non-recurring appointments work ok.
Troubleshooting: Unable to Change AppointmentItem.Start Property


When working with Outlook applications, it's not uncommon to encounter issues when attempting to modify the AppointmentItem.Start property. This can be a frustrating roadblock for many developers and users alike. In this article, we'll explore the common reasons behind this problem and provide step-by-step solutions to resolve it.

Step 1: Understanding the Issue

  1. What Causes the Issue? The inability to change the AppointmentItem.Start property often arises due to conflicting permissions or restrictions within the Outlook environment.
  2. Is this a Common Problem? Yes, this issue is encountered by a significant number of Outlook users, particularly those who interact with the Outlook API for scheduling and managing appointments.
  3. How Does it Impact Users? For developers and users, this issue can lead to difficulties in managing their schedules effectively. It can also hinder the automation of tasks related to appointments.
Step 2: Troubleshooting Solutions

  1. Check User Permissions Ensure that the user account you are using has the necessary permissions to modify calendar events. This can be done by verifying the account's settings in the Outlook application.
  2. Verify Object References Double-check that you are working with the correct AppointmentItem object. Incorrect references can lead to unexpected behavior.
  3. Review Synchronization Settings If you're working in a synchronized environment, ensure that there are no conflicts between the local and server copies of the calendar item.
  4. Handle Exceptions Implement appropriate exception handling in your code to gracefully manage any errors that may occur when attempting to modify the AppointmentItem.Start property.
  5. Debugging Tools Utilize debugging tools provided by your development environment to step through your code and identify any logical errors. Click
  6. Check for Add-ins or Extensions Sometimes, third-party add-ins or extensions can interfere with the normal behavior of Outlook. Temporarily disable any such add-ins to see if they are causing the issue.
Step 3: Helpful Resources

For more in-depth information on Outlook API and related troubleshooting, refer to the following articles:

  • Understanding Outlook API
  • Troubleshooting Outlook Integration

Resolving the issue of being unable to change the AppointmentItem.Start property is crucial for smooth scheduling and calendar management within the Outlook environment. By following the steps outlined in this article, you can overcome this obstacle and ensure that your application interacts seamlessly with the Outlook API. Remember to always check for updates or patches from Microsoft, as they may release fixes for known issues related to Outlook integration.
Found a way to modify the starting date of a recurring appointment. Here' how it's done:
1) Determine if the appointment item is recurring using the .IsRecurring property of the AppointmentItem object.
2) if IsRecurring is True, then use the .PatternStartDate property of the RecurrencePattern object to set the new start date for the recurring series and save the changed AppointmentItem.
3) To modify properties of the next or other occurrence, must create another instance of the AppointmentItem object and use GetOccurrence property (date) of RecurrencePattern object to access that item.

Must immediately set object instances to 'nothing' after done modifying the items. More info here: AppointmentItem.GetRecurrencePattern method (Outlook). Code example:

Dim olItem as AppointmentItem
Dim olRecurrencePattern As RecurrencePattern
'possible code here to figure out date offset or take input from user
'rdate is offset to existing start date of appointment or recurring series
If olItem.IsRecurring Then
Set olRecurrencePattern = olItem.GetRecurrencePattern
olRecurrencePattern.PatternStartDate = rdate1 'adding offset to prior start date doesn't affect start time
olItem.Start = rdate1
End If
Set olItem = Nothing
Set olRecurrencePattern = Nothing
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