Outlook randomly deletes calendar appointments and will not restore them

Question

Outlook randomly deletes calendar appointments and will not restore them

Frank Powell 0

Outlook Classic randomly deletes calendar appointments and will not restore them.

If I catch this within 30 days, I can see the deleted item in "Recover items . . .", but the restoration does not work. If I attempt to restore the item, it disappears from the "Recover items . . ." listing and yet doesn't actually get restored.

How can I prevent the unrequested deletions and how can I successfully restore such an item.

Please don't suggest using New Outlook, since it has much less function in calendar management.

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Answer 1

Vikki-T 9,585 Microsoft External Staff Moderator

Hi Frank Powell,

It must be frustrating to have calendar appointments disappear unexpectedly and then be unable to restore them. I understand that you prefer to continue using classic Outlook, so the suggestions below do not require switching to new Outlook.

To help narrow this down, could you please confirm:

Are you using an Outlook.com/Hotmail account, Microsoft 365 Personal or Family, or a work/school account?
Are the missing items appointments you created yourself, or meeting invitations sent by someone else?
Do the appointments also disappear when you check your calendar in Outlook on the web, or are they missing only in classic Outlook?
Is the same account connected to another computer, a mobile device, or a third-party calendar app?
Does this happen in your main calendar or a shared calendar?
Which version and build of classic Outlook are you using? You can find this under File > Office Account > About Outlook.

In the meantime, please try the following:

Sign in to Outlook on the web and check whether the missing appointment is still visible there. This will help determine whether the issue is limited to classic Outlook or whether the item has also been removed from the mailbox.
After attempting to recover an appointment, search for its exact subject across your mailbox. Please also check Deleted Items and any other calendars, in case the item was restored to a different location.
Try recovering one affected appointment through Outlook on the web instead of classic Outlook. You can refer to Microsoft’s instructions for recovering deleted items in Outlook.
Temporarily close Outlook and other calendar apps on your additional devices, then monitor whether appointments continue to disappear. This can help identify whether another connected device or app is syncing the deletion.
Start classic Outlook in Safe Mode by pressing Windows key + R, entering outlook.exe /safe, and selecting OK. If the behavior does not occur in Safe Mode, an Outlook add-in may be involved.

For now, please avoid permanently deleting any additional affected items. Let me know the answers to the questions above, particularly whether the appointments are also missing in Outlook on the web, and we can narrow down the next steps. Thank you so much for your understanding.

Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.

Vikki-T 9,585 Reputation points Microsoft External Staff Moderator

2026-09-02T11:29:59.89+00:00

Hi Frank Powell,

It has been a while and I am writing to see how things are going with this issue.

Have you had a chance to check the replies provided?

Any update would be appreciated.
Frank Powell 0 Reputation points

2026-09-08T03:56:56.63+00:00
No, nothing has helped yet. There are three related Outlook Classic issues:

The unsolicited deletion of Calendar Items.

Not retaining the self-deleted Calendar Item into Deleted Items. (Instead, it moves them directly to the Recover Deleted Items group.)

Permanently deleting items when I request Restore Selected Items. (The restoration doesn't place the calendar item onto any of my calendars on any of my deives.)

I can currentlysee a recently (unsolicited deletion) calendar item inside the Recover Deleted Items listing, and it shows the deletion as being 8/31/26 in a large group of deletions occurring at the same time (while I was not using any technology). Yet, I am afraid to recover it since past attempts to Recover Selected Items has permanently removed items from view.
Vikki-T 9,585 Reputation points Microsoft External Staff Moderator

2026-09-08T10:41:40.1766667+00:00

Hi Frank Powell,

Thank you for the detailed update. Since multiple calendar items appear to have been deleted at the same time on August 31, and restoring them removes them from Recover Deleted Items without returning them to any calendar, please do not attempt to restore the remaining item for now. Keeping it visible may be helpful for further investigation.

Could you please confirm whether this is an Outlook.com/Hotmail account, a Microsoft 365 Personal or Family account, or a work/school account? Also, when you check Outlook on the web, do you see the same deletion group and the same behavior when restoring an item?

As a next step, please run the Classic Outlook calendar check troubleshooter from Microsoft’s Classic Outlook troubleshooters page. You may also check whether your Outlook version is fully updated under File > Office Account > Update Options > Update Now.

If the same issue is present in Outlook on the web, or the troubleshooter does not identify the cause, this will likely require mailbox-level investigation by Microsoft Support. When contacting Support, please provide the deletion date shown in Recover Deleted Items, the approximate time of the grouped deletions, and explain that selecting Restore Selected Items removes the appointment from the recovery list without returning it to any calendar.

Please note that this is a user-to-user support forum. Moderators and community contributors do not have access to mailbox logs or back-end tools needed to trace what deleted the appointments or recover items that no longer appear after restoration.

You can contact Microsoft Support through Microsoft Support. If you encounter any difficulty reaching the appropriate support team, let me know what happens and I will try to help with the available options.
Frank Powell 0 Reputation points

2026-09-08T19:28:51.4433333+00:00
I have not attempted to recover the one specific item that I know is missing from my calendar. (Most of the items deleted in a batch on 8/31/26 at 8:39am (or 8:40am) were junk messages that I would have deleted or did delete. And, some of them are listed in the Recover Deleted Items list but are actually still correctly inside the Calendar.)

This is an Outlook.com account.

The auto-deleted items from 8/31/26 at 8:39am (or 8:40am) are not listed in the online version of Recover Deleted Items.

I ran the Advanced Diagnostics Troubleshooter, yet it didn’t create a report in the GetHelp folder which it opened.

I ran the Outlook update as suggested.

I spoke directly with a Microsoft Support agent approximately 9/1/26 but he was helpless.
Vikki-T 9,585 Reputation points Microsoft External Staff Moderator

2026-09-09T08:49:24.3466667+00:00
Hi Frank Powell,

Thank you for providing these details and for trying the suggested steps.

The fact that some items appear in Recover Deleted Items while still remaining correctly in the Calendar, together with the missing items not appearing in the online recovery list, suggests that this cannot be fully diagnosed through the forum. Since you have already updated Outlook, run the diagnostic tool, and checked Outlook on the web, I do not want to ask you to repeat the same steps.

Please keep the remaining affected item unchanged for now. I would also recommend taking screenshots of:

The item shown in Recover Deleted Items

The item’s deletion date and time

Any calendar items that appear in both the recovery list and the Calendar

Please make sure to hide any personal information before sharing screenshots publicly.

As the previous Support contact did not resolve the issue, you may need to contact Microsoft Support again and provide the previous case number. Clearly mention that this is an Outlook.com mailbox issue involving unsolicited calendar deletions and inconsistent Recover Deleted Items behavior across classic Outlook and Outlook on the web. You can also ask whether the case can be reviewed by a team with access to mailbox-level diagnostics.

Unfortunately, this user-to-user forum does not have access to mailbox logs or back-end recovery tools, so I cannot determine what initiated the deletion or restore an item that is no longer available through the online recovery list.

I know this isn't the news you were hoping for, but I wanted to make sure you got the most accurate information about your situation. Thank you so much for your cooperation.