Outlook doesn't preserve iCal UID for events where invited from Google Calendar

Question

Outlook doesn't preserve iCal UID for events where invited from Google Calendar

Omid Rooholfada 1

When my Outlook calendar gets invited to an event from a Google calendar, the event that gets created on my Outlook calendar has a different iCalUID from the corresponding event in GCal.

However, the ID is preserved when my Google calendar gets an invite from Outlook. This makes me think that Outlook is parsing the .ics invitation incorrectly and not preserving iCalUID.

This behavior defeats the purpose of the iCal UID - having a global ID for events across calendars.

Any insight on why this discrepancy is happening?

Deva-MSFT 2,271 Reputation points Microsoft Employee

2021-06-02T18:21:11.117+00:00

Adding right tags/teams to assist
ChristyZhang-MSFT 26,121 Reputation points Microsoft External Staff

2021-06-03T06:29:02.54+00:00

Hi @Omid Rooholfada ,

Please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. Looks like your issue might be more related to iCal UID. In order to better solve your problem, we will remove "Office Outlook ITpro" tag, and add "office-vba-dev", "office-js-dev" and "microsoft-graph-calendar"tag.

Thanks for your understanding and hope your question will be resolved soon!
Sarfaraz Suleman 1 Reputation point

2021-08-30T16:24:24.067+00:00
I am working on a calendar sync application and was having the same issue with implementing de-duplication between shared G-Cal and Outlook calendar events.

My solution (that is still in progress at the moment) is to look for the .ics attachment on the event. The .ics attachment contains the Original Google iCalUID.

Summarized workflow:

If a calendar event comes in from Outlook and the organizer is not the current calendar subscriber (i.e. event was created by another user), then check for the .ics attachment.

If no .ics attachment found, use the iCalUID included in the event payload.

If .ics found, use the iCalUID from the .ics attachment.

Lastly, in order to save API calls to attachments for event changes, I have a mapping table in my DB that matches iCalUID to Outlook iCalUID. This way, I can save myself a trip to the API by performing a DB lookup first.

Hope that helps.

Also, Microsoft knows of this as an issue and had the fix as part of their roadmap last year https://developer.microsoft.com/en-us/outlook/blogs/microsoft-graph-calendar-events-icaluid-update/

However, it was postponed https://developer.microsoft.com/en-us/outlook/blogs/deferred-icaluid-update-on-ms-graph/ and they have not conveyed any new updates ☹️

Your answer

Deva-MSFT 2,271 Reputation points Microsoft Employee

2021-06-02T18:21:11.117+00:00

Adding right tags/teams to assist
ChristyZhang-MSFT 26,121 Reputation points Microsoft External Staff

2021-06-03T06:29:02.54+00:00

Hi @Omid Rooholfada ,

Please kindly understand that the Outlook tag here we mainly focus on general issues about Outlook desktop client. Looks like your issue might be more related to iCal UID. In order to better solve your problem, we will remove "Office Outlook ITpro" tag, and add "office-vba-dev", "office-js-dev" and "microsoft-graph-calendar"tag.

Thanks for your understanding and hope your question will be resolved soon!
Sarfaraz Suleman 1 Reputation point

2021-08-30T16:24:24.067+00:00

I am working on a calendar sync application and was having the same issue with implementing de-duplication between shared G-Cal and Outlook calendar events.

My solution (that is still in progress at the moment) is to look for the .ics attachment on the event. The .ics attachment contains the Original Google iCalUID.

Summarized workflow:

If a calendar event comes in from Outlook and the organizer is not the current calendar subscriber (i.e. event was created by another user), then check for the .ics attachment.

If no .ics attachment found, use the iCalUID included in the event payload.

If .ics found, use the iCalUID from the .ics attachment.

Lastly, in order to save API calls to attachments for event changes, I have a mapping table in my DB that matches iCalUID to Outlook iCalUID. This way, I can save myself a trip to the API by performing a DB lookup first.

Hope that helps.

Also, Microsoft knows of this as an issue and had the fix as part of their roadmap last year https://developer.microsoft.com/en-us/outlook/blogs/microsoft-graph-calendar-events-icaluid-update/

However, it was postponed https://developer.microsoft.com/en-us/outlook/blogs/deferred-icaluid-update-on-ms-graph/ and they have not conveyed any new updates ☹️

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Outlook doesn't preserve iCal UID for events where invited from Google Calendar

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