Office 365 Outlook “When an event is added, updated or deleted (V3)” suddenly fails with 400

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Posted on by CU11050213-0

12 Microsoft Employee

Hi everyone,

One of my Power Automate cloud flows started failing suddenly a few days ago. The flow uses the Office 365 Outlook calendar change trigger:

Connector: Office 365 Outlook
Trigger operationId: CalendarGetOnChangedItemsV3
Trigger: When an event is added, updated or deleted (V3)
Parameters:
- incomingDays: 90
- pastDays: 15
splitOn: @triggerOutputs()?['body/value']

The trigger was working before, but now the trigger fails with HTTP 400.

Error response:

{
  "statusCode": 400,
  "body": {
    "status": 400,
    "message": "Office 365 calendar does not support change trigger.\r\nclientRequestId: [redacted]\r\nserviceRequestId: [redacted]",
    "errors": []
  }
}

The Korean localized message is:

Office 365 일정은 변경 시 트리거를 지원하지 않습니다.

I would like to know:

Did Microsoft recently change the behavior or support scope of CalendarGetOnChangedItemsV3?
Is this trigger no longer supported for shared calendars, resource calendars, room calendars, or Microsoft 365 Group calendars?
Is this a known temporary issue with the Office 365 Outlook connector?
If this trigger is not reliable anymore, is the recommended workaround to use a scheduled recurrence flow and poll calendar events instead?

I have not changed the flow logic recently. The failure appears to happen at the trigger level, before the flow actions run.

Any confirmation or workaround would be appreciated.

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Using connectors

Using flows

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Vish WR 3,110 on at

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@CU11050213-0

The error “Office 365 calendar does not support change trigger” (HTTP 400) is a known limitation/behavior change of the “When an event is added, updated or deleted (V3)” trigger.

Microsoft has documented that this trigger is not fully reliable across all calendar types and can fail or behave inconsistently depending on mailbox type (shared, resource, group calendars).

It can also break due to Graph/delta sync behavior changes, which affects how calendar changes are detected.

https://learn.microsoft.com/en-us/connectors/office365/

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DF-13051505-0 5 on at

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@Vish WR I don't see any information in that link indicating this is a known issue. Can you link the specific location?

This is quite frustrating... There's no native way to sync group calendars and o365 calendars, I got this working for a total of 2 days and after no changes from my side, it's not working. It appears there is no trigger for event deletions except for this trigger, and HTTP request triggers require a premium license...

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Vish WR 3,110 on at

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@CU11050213-0

There are few reports for similar issues with the “When an event is added, updated or deleted (V3)” trigger, especially for shared, group, and resource calendars due to backend Graph/Exchange limitations.

I would recommend using a scheduled/recurrence flow instead of relying on the trigger. You can periodically use “List events” or “Get calendar view of events (V3)” and compare event states to detect additions, updates, and deletions more reliably.

You can also raise a support ticket with Microsoft. You can raise a ticket from admin center.

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TR-14051949-0 6 on at

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I made a flow last week that made a matching task when I added an event to my calendar with certain keywords. Worked fine. Tried to make another flow today with a different keyword and now getting this same error. Seems like something must have changed recently.

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babychick 57 on at

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I have same problem. Worked on May 8 Friday and stopped working on May 11 Monday.

The flow has been working for months, and nothing have changed including the calendar.

Trigger: When an event is added, updated or deleted (V3)

Error:

{

    "statusCode": 400,

    "headers": {

        "Cache-Control": "no-store, no-cache",

        "Pragma": "no-cache",

        "Set-Cookie": "[redacted];Path=/;HttpOnly;Secure;Domain=office365-eus.azconn-eus-003.p.azurewebsites.net,ARRAffinitySameSite=[redacted];Path=/;HttpOnly;SameSite=None;Secure;Domain=office365-eus.azconn-eus-003.p.azurewebsites.net",

        "Strict-Transport-Security": "max-age=31536000; includeSubDomains",

        "x-ms-request-id": "[redacted]",

        "X-Content-Type-Options": "nosniff",

        "X-Frame-Options": "DENY",

        "x-ms-environment-id": "[redacted]",

        "x-ms-tenant-id": "[redacted]",

        "x-ms-subscription-id": "[redacted]",

        "x-ms-dlp-re": "-|-",

        "x-ms-dlp-gu": "-|-",

        "x-ms-dlp-ef": "-|-/-|-|-|-",

        "x-ms-mip-sl": "-|-|-|-",

        "x-ms-au-creator-id": "[redacted]",

        "Timing-Allow-Origin": "*",

        "x-ms-apihub-cached-response": "false",

        "x-ms-apihub-obo": "false",

        "x-ms-plex-failed": "400",

        "Date": "Sat, 16 May 2026 16:38:40 GMT",

        "Content-Length": "271",

        "Content-Type": "application/json",

        "Expires": "-1"

    },

    "body": {

        "status": 400,

        "message": "Your Office 365 calendar doesn't support the on change trigger.\r\nclientRequestId: [redacted]\r\nserviceRequestId: [redacted]",

        "errors": []

    }

}

If anyone has solution please let me know.

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KF-18050430-0 6 on at

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In my case, using it from Japan, the date and time obtained for this event was in GMT, but for some reason it was changed to Tokyo time from May 11. And on May 18, I could no longer retrieve the event due to the same error. Could there have been some specification change after all?

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DJ-18051544-0 12 on at

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Gday Everyone,

I thought I was going mad as well until I found this thread.

On Friday 15 May I noticed that it started returning "native" time instead of UTC. I had logic that was converting it from UTC to native which all of a sudden everything was in the wrong time zone.

I went back in to fix the logic to no longer convert from UTC tested it and it worked fine but then 1 day later it failed with the same error message.

This was working fine for months I even created logic to deal with all the duplicate events noise.

This is being done on my personal e-mail account so no fancy mailbox which are being excluded above.

When is Microsoft going to fix this ?

Your Office 365 calendar doesn't support the on change trigger.
clientRequestId: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX
serviceRequestId: XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX

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ericwhitley 155 on at

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I have been using this connector for approximately 4.5 YEARS and today I'm getting the same error as everyone else, "Your Office 365 calendar doesn't support the on change trigger."

Last week I also noticed the change in date format from everything being in UTC, to now getting start and end dates in the local time zone.

Something has definitely changed within Microsoft, either with this Connector or with the format of the data in the shared calendar we're accessing.

The errors started on May 18, 2026 after 7:05AM PDT. (That's the time of the last successful run.) Since that time, I see hundreds of entries in the "Failed Checks" view.

Things I have tried to resolve this: (These steps have helped resolve previous problems with the connector.)

Deleting the connector and re-adding it

Changing the Connection Reference to a different account

Turning the Flow off/on

Saving a copy of the flow

(All of the above simultaneously)

I cannot change this to use a scheduled flow at this time, does anybody have any quick solutions?

Thanks

UPDATE: On 5/19/2026 at 9:22AM Pacific, the flow starting running again and receiving valid data. We will keep watching it to make sure there are no errors or stoppages.

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AR-18051901-0 2 on at

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I have the same problem with my Outlook Calendar. Your Office 365 calendar doesn't support the on change trigger.

I use a similar construct for my google calendar with exactly the same construct and this connector still works.
=> This is definitely a change in Microsoft 365 Calendar behavior.

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babychick 57 on at

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I submitted a ticket this morning and was reached out by Microsoft Team member and we had a meeting where he took screenshots and additional information. He said he tried building flow on his end, and it did not work for him. He also mentioned that there are multiple similar tickets he is working on. He is reaching out to product managers as he believes this connector will need a fix and most likely will update us tomorrow.

Assuming connector needs to be fixed, what is typical timeline? I need to decide whether I need to look into alternate solution meanwhile. Also, if someone was able to figure how to make it work, that would help a lot.

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