"UnknownError " while accessing Graph API to get mailbox messages of the specific user with grant ty

I am trying to get the messages from outlook mailbox of a specific user. I created an app with permissions type "application" and permissions Mail.ReadBasic.All, Mail.Read, Mail.ReadWrite. I provided adminconsent with below url:

https://login.microsoftonline.com/{tenant}/adminconsent?client_id={}&secret_id={}&state=12345&redirect_uri=http://localhost:3000/myapp

and it returned adminconsent=true.

I am able to generate the token with https://login.microsoftonline.com/{tenant}/oauth2/v2.0/token.

But when acccessing graph api I am getting unknown error.

https://graph.microsoft.com/v1.0/users/{mail id}/mailfolders/inbox/messages
Header : Authorization = Bearer ey....

Error:

{   "error": {
    "code": "UnknownError",
    "message": "",
    "innerError": {
      "request-id": "62f75bdd-948b-4f35-a400-cbc1650d37f7",
      "date": "2020-01-31T07:00:00"
    }   } }