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.

Categories:

Using connectors

Using flows

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Vish WR 2,827 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 2,827 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 2 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 32 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 2 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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