Outlook invites failing due to object type error

Question

Outlook invites failing due to object type error

Support Rookie 0

Whenever internal or external users try to invite a user to an event, it fails because Outlook thinks it's trying to turn a Microsoft Calendar Object into an IPF.Note. I can't seem to find any calendars set to use IPF.Note. They are the only user with this issue.

NDR error message:
Remote server returned '554 5.2.0 STOREDRV.Deliver.Exception:WrongObjectTypeException; Failed to process message due to a permanent exception with message [BeginDiagnosticData]The object was bound to a wrong object type. ObjectClass = IPF.Note, Intended Type = Microsoft.Exchange.Data.Storage.CalendarFolder. WrongObjectTypeException: The object was bound to a wrong object type. ObjectClass = IPF.Note, Intended Type = Microsoft.Exchange.Data.Storage.CalendarFolder.[EndDiagnosticData] [Stage: OnCreatedEvent][Agent: Meeting Message Processing Agent]'

User's calendars:
PS> Get-MailboxFolderStatistics -Identity "[*****@domain.com]" -ResultSize Unlimited | Where-Object {$_.FolderPath -like "/Calendar"} | Select-Object Name,FolderPath,FolderType,ContainerClass,ItemsInFolder | Format-Table -Wrap -AutoSize

Name FolderPath FolderType ContainerClass ItemsInFolder

Calendar /Calendar User Created IPF.Appointment 929

Birthdays /Calendar/Birthdays BirthdayCalendar IPF.Appointment.Birthday 22

Calendar Logging /Calendar Logging CalendarLogging 136

0 comments

2 answers

Your answer

Answer 1

Support Rookie 0

A coworker solved this one by running outlook.exe /profile "outlook profile" /resetfolders a few times. Posting this to help anybody else who deals with this issue.

outlook.exe /profile "Joe Profile" /resetfolders

0 comments

Answer 2

Hi Support Rookie,

Thank you for sharing the NDR and the mailbox folder statistics.

Since the failure occurs when both internal and external users send meeting invitations, the issue appears to be on the affected mailbox rather than with the sender or the Outlook client.

If you are the Microsoft 365 administrator, you can run the following command to collect additional Calendar folder details:

Get-MailboxFolderStatistics -Identity ******@domain.com -FolderScope Calendar |  
Select-Object Name,FolderPath,FolderType,ContainerClass,FolderId,ItemsInFolder

You may also test the affected mailbox in Outlook on the web by opening the Calendar and creating a test appointment. However, do not delete or recreate the current Calendar folder, as it contains existing calendar items and may be linked to the mailbox’s default-folder configuration.

If the /Calendar folder continues to appear as User Created, or invitations continue to fail with the same WrongObjectTypeException, I recommend that your Microsoft 365 administrator open a support request with Microsoft Support through Microsoft 365 Admin Center > Support > Help & support. They have access to backend configurations and can perform a more in-depth investigation. At the very least, they can provide the most effective workaround to ensure your experience remains smooth and secure.  

When opening the request, please include the complete NDR, message trace details, the PowerShell output, and the date and time of a recent failed invitation.

For detailed guidance on how to open a support ticket with Microsoft Support, please refer to: Get support - Microsoft 365 admin | Microsoft Learn
In case you do not know who is your IT admin, kindly refer to this article: How do I find my Microsoft 365 admin? - Microsoft Support

I hope this information helps move the case forward. Should you have any further questions or need additional assistance, please feel free to share them in the comment below. I'm very happy to help.

If the answer is helpful, please click 'Yes' and kindly upvote it.

Note: Follow the steps in the forum documentation to enable email notifications if you want to receive email notifications related to this topic.

Support Rookie 0 Reputation points

2026-10-06T16:46:51.2366667+00:00

The user's calendar is their Outbox. Can I safely remediate this without data loss for them?

PS> Get-MailboxFolderStatistics -Identity ******@domain.com -FolderScope Calendar | Select-Object Name,FolderPath,FolderType,ContainerClass,FolderId,ItemsInFolder

Name : Outbox

FolderPath : /Outbox

FolderType : Outbox

ContainerClass :

FolderId : LgAAAADJdgtMIkvRTYji1dC0mzS6AQDcTS5VSL9jTpo/MHCB142nAAAAAAELAAAB

ItemsInFolder : 30
Jack-Bu 6,865 Reputation points Microsoft External Staff Moderator

2026-10-06T17:23:36.53+00:00

Hi Support Rookie,

Thank you for sharing the updated PowerShell output. This result is significant because the Calendar-scoped query is returning the user’s /Outbox folder with FolderType: Outbox, rather than a Calendar folder.

This suggests that the mailbox’s internal default-folder mapping may be incorrect or corrupted, which would also explain why Exchange encounters a WrongObjectTypeException when processing meeting invitations.

Since the Outbox currently contains 30 items, I would not recommend deleting, recreating, renaming, or modifying either the Outbox or Calendar folder through Outlook, PowerShell, or MFCMAPI. Without confirming what those items are and how the default folders are mapped internally, these actions could result in data loss or further mailbox folder issues.

You may first preserve the mailbox data by confirming that mailbox retention or backup is available and, if possible, exporting any accessible calendar items. However, I would recommend opening a support request with Microsoft before attempting remediation.

When opening the request, include:

The complete WrongObjectTypeException NDR

Both Get-MailboxFolderStatistics outputs

The affected mailbox address

A recent failed invitation’s date, time, time zone, and message trace details

Confirmation that -FolderScope Calendar returns /Outbox

Confirmation that the Outbox currently contains 30 items

Based on the current output, I would not consider a client-side Outlook repair, profile recreation, or folder deletion to be an appropriate remediation, because the incorrect folder association appears to exist within the mailbox itself.

I hope this can be resolved soon.