Graph API /createImportSession request

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Graph API /createImportSession request

val19680507 21

Hi All,

I use Graph API /createImportSession request and then the returned "importUrl" to replace EWS functionality <m:UploadItems>.

It works for messages and contacts but not for events.

I.e. I can read events with /exportItems but can't upload them with /createImportSession and then "importUrl". It returns unknown error.

So question - is such behavior correct and upload functionality is not implemented in Graph API for events or it's some problem on my side? If so, what can it be?

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Answer 1

Anthony Porter 390

createImportSession supports importing Outlook items such as messages and contacts, but calendar events are not currently supported through the same import workflow. This aligns with what you're seeing: exportItems can export events, however attempting to upload an event through the importUrl generated by createImportSession results in a failure.

If your goal is to migrate or recreate calendar items, the supported approach is typically to create events via the Calendar APIs (POST /users/{id}/events or related calendar endpoints) rather than using the import session mechanism.

val19680507 21 Reputation points

2026-09-20T13:52:23.73+00:00

Thanks Anthony for your answer.

Can you also explain what is difference in calendar item from contact or mail item what prevented them from being imported in the same way? And if such functionality, to import calendar items, is planned in nearest future?

Also there is another unclear behavior which concerns only calendar folders. We convert EWS IDs to Graph IDs with API call /translateExchangeIds when we upgrade our app. In fact it just replace '+' to '_' and '/' to '-'.

But then if user select ID of calendar folder via other API like /users/{mailbox_addr}/calendar - it returns another ID. And it leads to problems.

Interesting that for mail and contacts folders no such problem.

Is it MS bug and can it be fixed?
Anthony Porter 390 Reputation points

2026-09-21T22:40:47.8466667+00:00

As far as I'm aware, Microsoft hasn't mentioned any plans to add calendar event support to createImportSession. Calendar items are managed through the dedicated Calendar APIs, which is why events can be exported with exportItems but not re-imported through the same workflow.
https://learn.microsoft.com/en-us/answers/questions/6004103/graph-api-createimportsession-request

For the folder ID behaviour, I wouldn't call it a 'bug'. Calendar folders are exposed differently to mail and contact folders, so seeing a different ID returned from /users/{mailbox}/calendar compared to a translated EWS ID is probably expected. Without sample IDs, it's difficult to confirm whether it's by design or an issue.