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How to get seriesId from meeting instance iCalUid

Vishal Mishra 0 Reputation points Microsoft Employee
2026-06-16T15:11:47.1633333+00:00

Hi,

I am using GET /me/events?$filter=uid eq '<instance_icaluid_here>' to get the seriesMaster Event. Could someone confirm the below statements:

  • The response returned is indeed the seriesMaster event.
  • The uid of the response is the id of that series event

Also what does icaluid of that response indicates? This response's icaluid changes for persons who are part of the series vs one instance attendees/invitees.

Microsoft 365 and Office | Development | Other
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  1. Dora-T 14,950 Reputation points Microsoft External Staff Moderator
    2026-06-17T04:41:27.9833333+00:00

    Hi Vishal Mishra

    Thank you for reaching out to the Microsoft Q&A Forum.

    Please note that this is a user-to-user support forum. While moderators and community members can share guidance based on documentation and experience, we do not have direct access to the Microsoft Graph engineering team or internal implementation details. 

    From the documentation I reviewed: 

    • uid and iCalUId are separate properties in the Microsoft Graph event resource.  
    • For recurring events, the uid value is shared by the series master and all occurrences, including exceptions.  
    • iCalUId is a unique identifier across calendars and is different for each occurrence in a recurring series. 

    However, I could not find documentation that describes a supported relationship between an occurrence's iCalUId and the uid property, or that guarantees this query pattern is expected to resolve to the corresponding series master. 

    To gather additional perspectives on this behavior, you may also consider posting your question on the Microsoft Community Hub or on GitHub, where experienced engineers and contributors may be able to share their findings and experience. 

    Thank you 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.

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  2. AI answer

    2026-06-16T15:12:08.05+00:00

    uid and iCalUId are two different identifiers on an event:

    • uid (on the Microsoft Graph event resource and exposed by cmdlets such as New-MgBetaUserEvent via the Uid property) is a unique identifier for calendar events. For recurring events, this value is the same for the series master and all of its occurrences and exceptions.
    • iCalUId is a unique identifier for an event across calendars, and it is different for each occurrence in a recurring series.

    From the event schema in the Microsoft Graph PowerShell module:

    • Uid: “A unique identifier for calendar events. For recurring events, the value is the same for the series master and all of its occurrences including exceptions.”
    • ICalUId: “A unique identifier for an event across calendars. This ID is different for each occurrence in a recurring series. Read-only.”

    Based on that:

    1. If a query filters on uid and returns an event that represents the recurring series, that event is the series master. All instances in the series share the same uid value.
    2. The uid of that series master is not the “seriesId” in the sense of a separate property; it is the common identifier that ties the series master and all its occurrences together.
    3. The iCalUId on the series master identifies that event across calendars, but each individual occurrence has its own iCalUId, which is why iCalUId values differ between the series master and individual instances, and between different attendees’ copies of a specific occurrence.

    In other words:

    • Use uid when a single value is needed to represent the entire recurring series (master + all occurrences/exceptions).
    • Expect iCalUId to vary per occurrence and per attendee’s copy of that occurrence.

    References:

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