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Error code 500 without erorr message when using /findMeetingTimes route with timezone Europe/Kyiv. But works on route /calendar/getSchedule
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Daniel Stoll
25
Reputation points
Submitting a bug nearly got impossible for graph errors. So it is posted here now...
As per the docs, the graph apis do accept the timezone "Europe/Kyiv"
https://learn.microsoft.com/en-us/graph/api/resources/datetimetimezone?view=graph-rest-1.0#additional-time-zones
Most of the routes do actually support them. But not the /findMeetingTimes.
steps to reproduce
go to the graph explorer and log in
https://developer.microsoft.com/en-us/graph/graph-explorer
Add the route and change the method to post
https://graph.microsoft.com/v1.0/me/findMeetingTimes
as body select
{"attendees":[],"timeConstraint":{"timeSlots":[{"start":{"dateTime":"2025-06-05T10:30:00","timeZone":"Europe/Kyiv"},"end":{"dateTime":"2025-06-12T10:30:00","timeZone":"Europe/Kyiv"}}]}}
This will result in the error:
{
"error": {
"code": "UnknownError",
"message": "",
"innerError": {
"date": "2025-06-05T07:51:38",
"request-id": "997f3dd2-0823-4473-aef1-396b5f8a6d62",
"client-request-id": "08240f21-d3e2-2a67-88e7-117971ce931c"
}
}
}
This also happens if a non existing timezone is added like "Foo/Bar"
The one below however does work.
{"attendees":[],"timeConstraint":{"timeSlots":[{"start":{"dateTime":"2025-06-05T10:30:00","timeZone":"Europe/Kiev"},"end":{"dateTime":"2025-06-12T10:30:00","timeZone":"Europe/Kiev"}}]}}
Best,
Daniel
*Edited colors
Microsoft Security | Microsoft Graph
{count} votes
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Ki-lianK-7341 935 Reputation points2025-06-05T08:05:31.41+00:00 A 500 Internal Server Error without an error message when calling the
/findMeetingTimesendpoint (but not on/calendar/getSchedule) suggests the issue is likely with how the/findMeetingTimesAPI handles thetimeZoneparameter — especially if the problem only occurs withEurope/Kyiv.Common Causes & Fixes:
✅ 1. Unsupported or Invalid Time Zone Format
Some Microsoft Graph API endpoints are stricter than others about time zone formats. Try these:
- Use "Eastern European Standard Time" instead of "Europe/Kyiv"
-
Europe/Kyivis an IANA time zone, but Graph may expect a Windows time zone ID in certain endpoints like/findMeetingTimes.
-
Fix:
"timeZone": "Eastern European Standard Time"Check the official list of supported time zones — look for
displayNameandid.✅ 2. Mismatch Between Calendars and Time Zone
If your calendar or user mailbox settings are based on a Windows time zone (e.g., "Eastern European Standard Time"), but you pass an IANA time zone like "Europe/Kyiv", the API might silently fail.
Try matching the time zone used in
/findMeetingTimesto that used in/calendar/getSchedule(where it works).✅ 3. Missing TimeZone in Request Body (or Wrong Placement)
Make sure you're passing
timeZonein the right place, depending on the structure.Example correct format:
{ "attendees": [ { "type": "required", "emailAddress": { "address": "user@example.com" } } ], "timeConstraint": { "timeSlots": [ { "start": { "dateTime": "2025-06-10T09:00:00", "timeZone": "Eastern European Standard Time" }, "end": { "dateTime": "2025-06-10T17:00:00", "timeZone": "Eastern European Standard Time" } } ] }, "meetingDuration": "PT1H" }✅ Action Steps:
Replace
"Europe/Kyiv"with"Eastern European Standard Time"in your request body.Make sure all
dateTimefields include atimeZone.If using Graph SDKs, update to the latest version and inspect the raw HTTP request/response for more details.
- Use "Eastern European Standard Time" instead of "Europe/Kyiv"
-
TP 124.9K Reputation points Volunteer Moderator2025-06-05T08:17:06.0333333+00:00 @Ki-lianK-7341 Please update this answer as well as your other answers/comments to comply with AI Usage policy for Microsoft Q&A.
For example, you could start by clearly stating at the top of each answer that it is generated in whole/part by AI and detail which AI was used, similar to below:
AI generated content. This answer was created with AI from ChatGPT
Additionally, please make sure you comply with the other key elements of the policy, excerpted below:
Follow these steps when using AI to generate an answer on Q&A:
- Mention the AI service name that generated the answer, fully or partly.
- Check the AI output accuracy and relevance and adjust it as needed. Indicate you validated or updated the AI output in your answer.
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Using AI to help with answers on Microsoft Q&A requires following these three steps. Otherwise, moderators might delete the content and suspend your account.
Thank you.
-
Daniel Stoll 25 Reputation points
2025-06-05T08:32:25.2733333+00:00 Thanks for your quick response :)
The timeZone "Eastern European Standard Time" unfortunately does not work.
I tried a little bit more and found, that those are working: "FLE Standard Time" or "Europe/Kiev"Your link seems to be broken.
https://learn.microsoft.com/en-us/graph/api/resources/timezone?view=graph-rest-1.0
The other one that I used Lists the not working zone.
https://learn.microsoft.com/en-us/graph/api/resources/datetimetimezone?view=graph-rest-1.0#additional-time-zones
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