Azure AD Calendar API 401 Unauthorized Error - Need Help

Question

Azure AD Calendar API 401 Unauthorized Error - Need Help

Anthony Pitra 0

Problem Description

I'm getting a 401 Unauthorized error when trying to create calendar events using Microsoft Graph API with Azure AD authentication. The error occurs specifically when calling the /me/events endpoint to create calendar events.
When calling /me is working well.

Current Setup

Application Type: Web application using NextAuth.js
Authentication Flow: Authorization Code flow with PKCE
Scopes Requested: openid profile email offline_access https://graph.microsoft.com/User.Read https://graph.microsoft.com/Calendars.ReadWrite
Token Type: Delegated permissions (user-based)

Error Details

Status Code: 401 Unauthorized
Error: GraphError from @microsoft/microsoft-graph-client
Endpoint: /me/events (POST request)
Authentication: Azure AD OAuth2 with delegated permissions

Current Setup

Application Type: Web application using NextAuth.js
Authentication Flow: Authorization Code flow with PKCE
Scopes Requested: openid profile email offline_access https://graph.microsoft.com/User.Read https://graph.microsoft.com/Calendars.ReadWrite
Token Type: Delegated permissions (user-based)

What Works

User authentication succeeds
Can retrieve user profile (/me endpoint works)
Token is valid and not expired
Scopes include Calendars.ReadWrite

What Fails

Creating calendar events (/me/events POST) returns 401
Error body shows empty message
Status code: 401 Unauthorized

Rukmini 43,915 Reputation points Microsoft External Staff Moderator

2025-10-15T14:16:40.23+00:00
Hello @Anthony Pitra,

I understand that you are trying to call calendar API with required API permissions and still getting 401 error.

To check whether the scope is present in the access token, decode the token in https://jwt.ms/ and make sure the scope Calendars.ReadWrite is present.

Also, make sure to grant Calendars.ReadWrite API permission in the Microsoft Entra ID application:

If still the issue persists, make sure that the user has one of the active O365/M365 licenses that includes Exchange Online such as E1, E3, or E5.

Let me know if any further queries - feel free to reach out!
Rukmini 43,915 Reputation points Microsoft External Staff Moderator

2025-10-16T08:57:43.5066667+00:00

Hello @Anthony Pitra,

Following up to see if the above provided information helped. Please do let me know if you need any further assistance required.
Anthony Pitra 0 Reputation points

2025-11-01T09:26:54.5333333+00:00

Hello Rukmini,

Thank you for your response.

The first point has been verified — the scopes are correctly included in the access token.

However, your second point is a good catch. I’m unable to see any licenses associated with the users, even though I know they should have active ones. Do you have any idea what could cause this or how I can verify it properly?

Thank you for your help!

Best regards,
Rukmini 43,915 Reputation points Microsoft External Staff Moderator

2025-11-03T10:09:59.32+00:00
Hello Anthony Pitra,

Go to Azure Portal → Users → Select the user → Licenses

Here you can check the licenses assigned to the User.

Hope this helps!

Your answer

Rukmini 43,915 Reputation points Microsoft External Staff Moderator

2025-10-15T14:16:40.23+00:00

Hello @Anthony Pitra,

I understand that you are trying to call calendar API with required API permissions and still getting 401 error.

To check whether the scope is present in the access token, decode the token in https://jwt.ms/ and make sure the scope Calendars.ReadWrite is present.

Also, make sure to grant Calendars.ReadWrite API permission in the Microsoft Entra ID application:

If still the issue persists, make sure that the user has one of the active O365/M365 licenses that includes Exchange Online such as E1, E3, or E5.

Let me know if any further queries - feel free to reach out!
Rukmini 43,915 Reputation points Microsoft External Staff Moderator

2025-10-16T08:57:43.5066667+00:00

Hello @Anthony Pitra,

Following up to see if the above provided information helped. Please do let me know if you need any further assistance required.
Anthony Pitra 0 Reputation points

2025-11-01T09:26:54.5333333+00:00

Hello Rukmini,

Thank you for your response.

The first point has been verified — the scopes are correctly included in the access token.

However, your second point is a good catch. I’m unable to see any licenses associated with the users, even though I know they should have active ones. Do you have any idea what could cause this or how I can verify it properly?

Thank you for your help!

Best regards,
Rukmini 43,915 Reputation points Microsoft External Staff Moderator

2025-11-03T10:09:59.32+00:00

Hello Anthony Pitra,

Go to Azure Portal → Users → Select the user → Licenses

Here you can check the licenses assigned to the User.

Hope this helps!