You can't successfully dismiss calendar reminders in Outlook

Symptoms

When you try to dismiss calendar reminders in Microsoft Outlook, you discover that they can't be dismissed or that they keep reappearing.

Cause

This issue occurs when the Reminders folder or the reminder view is corrupted.

Resolution

To resolve this issue, use one or both of the following methods.

Method 1

Run the following command-line switch to delete the item:

outlook.exe /cleanreminders 

If this method doesn’t resolve the issue, go to Method 2.

Method 2

Delete the Reminders folder by using the Microsoft Exchange Server MAPI Editor (MFCMAPI). To do this, follow these steps:

  1. Download MFCMAPI from github (scroll down and then click Latest release).

  2. Exit Outlook.

  3. Open MFCMAPI.

  4. On the Tools menu, click Options, select both of the following check boxes (if they're not already selected), and then click OK:

    • Use the MDB_ONLINE flag when calling OpenMsgStore
    • Use the MAPI_NO_CACHE flag when calling OpenEntry
  5. Click Session, click Logon, select the profile that you want to change, and then click OK.

  6. Double-click the mailbox store that you want to open.

  7. Expand Root Container.

  8. Right-click the Reminders folder, and then click Delete folder.

    Note

    Do not delete the individual items inside the Reminders folder. The Reminders folder is just a view of upcoming events on the calendar. If the items inside the folder are deleted, those items will be removed from the calendar.

  9. Run the Outlook.exe /cleanreminders or Outlook.exe /ResetFolders command line. (This step re-creates the Reminders folder and adds any valid entries back in.)