The call list all calendars (/v1.0/me/calendars) returns a 500 Internal Server Error or 403.

[JeroenBer]

Describe the bug
The call list all calendars (/v1.0/me/calendars) returns a 500 Internal Server Error.

This call seems to no longer work for a lot of users, we get error reports from a lot of users.

I tried with 4 accounts:
personal live account -> error 500
personal outlook account -> error 403
personal hotmail account -> error 403
O365 account -> OK

This call no longer seems to work properly for personal outlook/live/hotmail accounts. Probably started in the last 24hours.

To Reproduce
Steps to reproduce the behavior:

1. Go to Microsoft Graph Explorer: https://developer.microsoft.com/en-us/graph/graph-explorer
2. Create a token for a personal outlook/hotmail/live account (not O365, that seems to work), consent to e.g. Calendar.Read scope
3. Go to "Outlook Calendar", list all calendars.
4. Click on "Run query".
5. See error, either 500 or 403 while haven given consent.

Expected behavior
No errors

Screenshots
500 for my account:

403 for another account while consenting

[ajtruckle]

I have this issue too with my calendar app. I get this exception when extracting a calendar list:

2025-06-01 20:42:47.4537|ERROR|MSATools.Graph.Outlook|Microsoft.Graph.Models.ODataErrors.ODataError: An internal server error occurred. The operation failed.
   at Microsoft.Kiota.Http.HttpClientLibrary.HttpClientRequestAdapter.ThrowIfFailedResponseAsync(HttpResponseMessage response, Dictionary`2 errorMapping, Activity activityForAttributes, CancellationToken cancellationToken)
   at Microsoft.Kiota.Http.HttpClientLibrary.HttpClientRequestAdapter.SendAsync[ModelType](RequestInformation requestInfo, ParsableFactory`1 factory, Dictionary`2 errorMapping, CancellationToken cancellationToken)
   at Microsoft.Kiota.Http.HttpClientLibrary.HttpClientRequestAdapter.SendAsync[ModelType](RequestInformation requestInfo, ParsableFactory`1 factory, Dictionary`2 errorMapping, CancellationToken cancellationToken)
   at Microsoft.Graph.Me.Calendars.CalendarsRequestBuilder.GetAsync(Action`1 requestConfiguration, CancellationToken cancellationToken)
   at MSATools.Graph.GraphHelper.BuildCalendarsList() in D:\My Programs\2022\MSATools\MSATools\Graph\GraphHelper.cs:line 87
   at MSATools.Graph.Outlook.BuildUserCalenderListAsync() in D:\My Programs\2022\MSATools\MSATools\Graph\Outlook.cs:line 43
2025-06-01 20:42:47.4865|INFO|MSATools.Program|Return code: "Exception"

Code:

public static async Task<CalendarCollectionResponse?> BuildCalendarsList()
{
    // Ensure client isn't null
    _ = _userClient ??
        throw new System.NullReferenceException("Graph has not been initialized for user auth");

        return await _userClient
                             .Me
                             .Calendars
                             .GetAsync();
}

This (return await _userClient) is line 87. I also tried reaching out on StackOverflow but my question was closed. This is a critical issue.

[ste7]

I'm experiencing the same issue

[iboughtbed]

same issue here

[Danielsan9998]

Same issue here

[jooooel]

Found this thread which mentions trying the beta endpoint, but that doesn't work either

https://learn.microsoft.com/en-us/answers/questions/2280189/i-am-getting-500-internal-server-error-on-https-gr

[JeroenBer]

According to our analytics at least 10K+ of our endusers are at least affected by this bug. So I would think it's very critical.

Is everyone experiencing the 500 ? Or ar people also experiencing the 403 ?

[JeroenBer]

Seems to be duplicate with #3860 and #3862

[DrBenvey]

same proble
none of v1.0 / beta didnt work

[VLoub]

Same here, i did some tests in powershell and i am unable to get other calendars beside Birthdays and my Shared calendar. As my pipeline runs every hour, I pinpointed the issue started in span 2025-06-01 05:34 (last success) 2025-06-01 06:34 (first fail), the datetimes are in CEST.

[TuanCLima]

same issue here

[M-Rapske]

Same...