Couldn't update the following event error when editing calendar items from OWA or Outlook

Original KB number:   4459263

Note

Microsoft 365 compliance is now called Microsoft Purview and the solutions within the compliance area have been rebranded. For more information about Microsoft Purview, see the blog announcement.

Symptoms

Consider the following scenario:

  • A user has a mailbox in Microsoft 365.
  • In-place hold or litigation hold is enabled for the mailbox.
  • The user tries to edit calendar items from Microsoft Outlook Web App (OWA) or Microsoft Outlook.

In this scenario, the user receives the following error message:

Couldn't update the following event:
<EventName>

Screenshot of the error message, showing Couldn't update the following event.

Cause

This issue occurs because the Versions folder (that is part of the Recoverable Items folder) is full.

Note

To check the Recoverable Items folder statistics, run the following command:
Get-MailboxFolderStatistics -Identity cloudtest -FolderScope recoverableitems | ft name,*size*

Resolution

Because the user's mailbox is on hold, the items in the Versions folder are very important. To resolve this issue, you have to enable the archive mailbox for the affected user, and then move all items of the Versions folder to the archive mailbox. To do this, follow these steps:

  1. Enable the archive mailbox. To do this, run Enable-Mailbox -IdentityUserName-Archive.

  2. Turn on the auto-expanding archiving feature. To do this, run Enable-Mailbox <UserMailbox> -AutoExpandingArchive.

    Note

    • Enabling the auto-expanding archiving for the mailbox increases the storage quota for the Recoverable Items folder in the user's primary mailbox by 10 GB (from 100 GB to 110 GB). Also, this step increases the archive mailbox size to unlimited.
    • A user's archive mailbox must be enabled before you can enable auto-expanding archiving. A user must be assigned an Exchange Online Plan 2 license to enable the archive mailbox. If a user is assigned an Exchange Online Plan 1 license, you have to assign to them a separate Exchange Online Archiving license to enable their archive mailbox.
  3. Create a custom retention policy for mailboxes on hold, and then move the items from the Versions folder to the archive mailbox. To do this, follow the steps that are mentioned in the Step 1: Create a custom retention tag for the Recoverable Items folder section of the following Docs article:

    Increase the Recoverable Items quota for mailboxes on hold

More information

When a user's mailbox is on in-place hold or litigation hold, original items and changed items are copied to the Versions folder. If the Versions folder is full, the changed copy of the original items cannot be stored in the folder. Therefore, the user cannot save changes to the original items.